diff --git a/modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java b/modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java
index a655184f89e7c..6ba8394e1e598 100644
--- a/modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java
+++ b/modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java
@@ -274,7 +274,7 @@ public PercolateQueryBuilder(String field, String documentType, String indexedDo
         }
         if (documents.isEmpty() == false) {
             if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                documentXContentType = XContentType.readFrom(in);
+                documentXContentType = in.readEnum(XContentType.class);
             } else {
                 documentXContentType = XContentFactory.xContentType(documents.iterator().next());
             }
@@ -331,7 +331,7 @@ protected void doWriteTo(StreamOutput out) throws IOException {
             out.writeOptionalBytesReference(doc);
         }
         if (documents.isEmpty() == false && out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            documentXContentType.writeTo(out);
+            out.writeEnum(documentXContentType);
         }
     }
 
diff --git a/server/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/PutStoredScriptRequest.java b/server/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/PutStoredScriptRequest.java
index e3392df885075..5ab5c49d0c791 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/PutStoredScriptRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/PutStoredScriptRequest.java
@@ -123,7 +123,7 @@ public void readFrom(StreamInput in) throws IOException {
         id = in.readOptionalString();
         content = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(content);
         }
@@ -145,7 +145,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalString(id);
         out.writeBytesReference(content);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
         if (out.getVersion().onOrAfter(Version.V_6_0_0_alpha2)) {
             out.writeOptionalString(context);
diff --git a/server/src/main/java/org/elasticsearch/action/index/IndexRequest.java b/server/src/main/java/org/elasticsearch/action/index/IndexRequest.java
index 46d51ee0b40e4..f2ddca1955878 100644
--- a/server/src/main/java/org/elasticsearch/action/index/IndexRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/index/IndexRequest.java
@@ -542,7 +542,11 @@ public void readFrom(StreamInput in) throws IOException {
         pipeline = in.readOptionalString();
         isRetry = in.readBoolean();
         autoGeneratedTimestamp = in.readLong();
-        contentType = in.readOptionalWriteable(XContentType::readFrom);
+        if (in.readBoolean()) {
+            contentType = in.readEnum(XContentType.class);
+        } else {
+            contentType = null;
+        }
     }
 
     @Override
@@ -566,7 +570,12 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalString(pipeline);
         out.writeBoolean(isRetry);
         out.writeLong(autoGeneratedTimestamp);
-        out.writeOptionalWriteable(contentType);
+        if (contentType != null) {
+            out.writeBoolean(true);
+            out.writeEnum(contentType);
+        } else {
+            out.writeBoolean(false);
+        }
     }
 
     @Override
diff --git a/server/src/main/java/org/elasticsearch/action/ingest/PutPipelineRequest.java b/server/src/main/java/org/elasticsearch/action/ingest/PutPipelineRequest.java
index 394349ca01691..10b19ed8cfa17 100644
--- a/server/src/main/java/org/elasticsearch/action/ingest/PutPipelineRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/ingest/PutPipelineRequest.java
@@ -81,7 +81,7 @@ public void readFrom(StreamInput in) throws IOException {
         id = in.readString();
         source = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(source);
         }
@@ -93,7 +93,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(id);
         out.writeBytesReference(source);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 }
diff --git a/server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java b/server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java
index 170f0bc8518cf..428df00a68e9c 100644
--- a/server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java
@@ -76,7 +76,7 @@ public SimulatePipelineRequest(BytesReference source, XContentType xContentType)
         verbose = in.readBoolean();
         source = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(source);
         }
@@ -123,7 +123,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeBoolean(verbose);
         out.writeBytesReference(source);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 
diff --git a/server/src/main/java/org/elasticsearch/action/termvectors/TermVectorsRequest.java b/server/src/main/java/org/elasticsearch/action/termvectors/TermVectorsRequest.java
index 9a26e63f1afd4..3aa7b832f1f4e 100644
--- a/server/src/main/java/org/elasticsearch/action/termvectors/TermVectorsRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/termvectors/TermVectorsRequest.java
@@ -516,7 +516,7 @@ public void readFrom(StreamInput in) throws IOException {
         if (in.readBoolean()) {
             doc = in.readBytesReference();
             if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                xContentType = XContentType.readFrom(in);
+                xContentType = in.readEnum(XContentType.class);
             } else {
                 xContentType = XContentFactory.xContentType(doc);
             }
@@ -561,7 +561,7 @@ public void writeTo(StreamOutput out) throws IOException {
         if (doc != null) {
             out.writeBytesReference(doc);
             if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-                xContentType.writeTo(out);
+                out.writeEnum(xContentType);
             }
         }
         out.writeOptionalString(routing);
diff --git a/server/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java b/server/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
index 9274bfbf345ae..e673c2a4b7ca2 100644
--- a/server/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
+++ b/server/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
@@ -593,7 +593,7 @@ public XContentBuilder field(String name, BytesRef value) throws IOException {
     /**
      * Writes the binary content of the given {@link BytesRef} as UTF-8 bytes.
      *
-     * Use {@link XContentParser#utf8Bytes()} to read the value back
+     * Use {@link XContentParser#charBuffer()} to read the value back
      */
     public XContentBuilder utf8Field(String name, BytesRef value) throws IOException {
         return field(name).utf8Value(value);
@@ -615,7 +615,7 @@ public XContentBuilder binaryValue(BytesRef value) throws IOException {
     /**
      * Writes the binary content of the given {@link BytesRef} as UTF-8 bytes.
      *
-     * Use {@link XContentParser#utf8Bytes()} to read the value back
+     * Use {@link XContentParser#charBuffer()} to read the value back
      */
     public XContentBuilder utf8Value(BytesRef value) throws IOException {
         if (value == null) {
diff --git a/server/src/main/java/org/elasticsearch/common/xcontent/XContentParser.java b/server/src/main/java/org/elasticsearch/common/xcontent/XContentParser.java
index dbeb678f3afad..a9037b74ce9ed 100644
--- a/server/src/main/java/org/elasticsearch/common/xcontent/XContentParser.java
+++ b/server/src/main/java/org/elasticsearch/common/xcontent/XContentParser.java
@@ -19,10 +19,9 @@
 
 package org.elasticsearch.common.xcontent;
 
-import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.common.lease.Releasable;
-
+import java.io.Closeable;
 import java.io.IOException;
+import java.nio.CharBuffer;
 import java.util.List;
 import java.util.Map;
 
@@ -37,7 +36,7 @@
  *          NamedXContentRegistry.EMPTY, ParserField."{\"key\" : \"value\"}");
  * </pre>
  */
-public interface XContentParser extends Releasable {
+public interface XContentParser extends Closeable {
 
     enum Token {
         START_OBJECT {
@@ -144,17 +143,13 @@ enum NumberType {
 
     String textOrNull() throws IOException;
 
-    /**
-     * Returns a BytesRef holding UTF-8 bytes or null if a null value is {@link Token#VALUE_NULL}.
-     * This method should be used to read text only binary content should be read through {@link #binaryValue()}
-     */
-    BytesRef utf8BytesOrNull() throws IOException;
+    CharBuffer charBufferOrNull() throws IOException;
 
     /**
-     * Returns a BytesRef holding UTF-8 bytes.
+     * Returns a {@link CharBuffer} holding UTF-8 bytes.
      * This method should be used to read text only binary content should be read through {@link #binaryValue()}
      */
-    BytesRef utf8Bytes() throws IOException;
+    CharBuffer charBuffer() throws IOException;
 
     Object objectText() throws IOException;
 
@@ -248,8 +243,6 @@ enum NumberType {
      *
      * these methods write UTF-8 encoded strings and must be read through:
      * <ul>
-     *     <li>{@link XContentParser#utf8Bytes()}</li>
-     *     <li>{@link XContentParser#utf8BytesOrNull()}}</li>
      *     <li>{@link XContentParser#text()} ()}</li>
      *     <li>{@link XContentParser#textOrNull()} ()}</li>
      *     <li>{@link XContentParser#textCharacters()} ()}}</li>
diff --git a/server/src/main/java/org/elasticsearch/common/xcontent/XContentType.java b/server/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
index 40caa6e911087..7196fdbf984e7 100644
--- a/server/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
+++ b/server/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
@@ -19,22 +19,18 @@
 
 package org.elasticsearch.common.xcontent;
 
-import org.elasticsearch.common.io.stream.StreamInput;
-import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.cbor.CborXContent;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.common.xcontent.smile.SmileXContent;
 import org.elasticsearch.common.xcontent.yaml.YamlXContent;
 
-import java.io.IOException;
 import java.util.Locale;
 import java.util.Objects;
 
 /**
  * The content type of {@link org.elasticsearch.common.xcontent.XContent}.
  */
-public enum XContentType implements Writeable {
+public enum XContentType {
 
     /**
      * A JSON based content type.
@@ -183,18 +179,4 @@ public String mediaType() {
 
     public abstract String mediaTypeWithoutParameters();
 
-    public static XContentType readFrom(StreamInput in) throws IOException {
-        int index = in.readVInt();
-        for (XContentType contentType : values()) {
-            if (index == contentType.index) {
-                return contentType;
-            }
-        }
-        throw new IllegalStateException("Unknown XContentType with index [" + index + "]");
-    }
-
-    @Override
-    public void writeTo(StreamOutput out) throws IOException {
-        out.writeVInt(index);
-    }
 }
diff --git a/server/src/main/java/org/elasticsearch/common/xcontent/json/JsonXContentParser.java b/server/src/main/java/org/elasticsearch/common/xcontent/json/JsonXContentParser.java
index d1075dd0173b0..70461e07ea151 100644
--- a/server/src/main/java/org/elasticsearch/common/xcontent/json/JsonXContentParser.java
+++ b/server/src/main/java/org/elasticsearch/common/xcontent/json/JsonXContentParser.java
@@ -23,7 +23,6 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonToken;
 
-import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.IOUtils;
 import org.elasticsearch.common.xcontent.DeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
@@ -88,8 +87,8 @@ public String text() throws IOException {
     }
 
     @Override
-    public BytesRef utf8Bytes() throws IOException {
-        return new BytesRef(CharBuffer.wrap(parser.getTextCharacters(), parser.getTextOffset(), parser.getTextLength()));
+    public CharBuffer charBuffer() throws IOException {
+        return CharBuffer.wrap(parser.getTextCharacters(), parser.getTextOffset(), parser.getTextLength());
     }
 
     @Override
@@ -114,7 +113,7 @@ public Object objectText() throws IOException {
     public Object objectBytes() throws IOException {
         JsonToken currentToken = parser.getCurrentToken();
         if (currentToken == JsonToken.VALUE_STRING) {
-            return utf8Bytes();
+            return charBuffer();
         } else if (currentToken == JsonToken.VALUE_NUMBER_INT || currentToken == JsonToken.VALUE_NUMBER_FLOAT) {
             return parser.getNumberValue();
         } else if (currentToken == JsonToken.VALUE_TRUE) {
@@ -124,8 +123,7 @@ public Object objectBytes() throws IOException {
         } else if (currentToken == JsonToken.VALUE_NULL) {
             return null;
         } else {
-            //TODO should this really do UTF-8 conversion?
-            return utf8Bytes();
+            return charBuffer();
         }
     }
 
diff --git a/server/src/main/java/org/elasticsearch/common/xcontent/support/AbstractXContentParser.java b/server/src/main/java/org/elasticsearch/common/xcontent/support/AbstractXContentParser.java
index 6d41c5b83da12..008dca1b537ca 100644
--- a/server/src/main/java/org/elasticsearch/common/xcontent/support/AbstractXContentParser.java
+++ b/server/src/main/java/org/elasticsearch/common/xcontent/support/AbstractXContentParser.java
@@ -19,7 +19,6 @@
 
 package org.elasticsearch.common.xcontent.support;
 
-import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.Booleans;
 import org.elasticsearch.common.Numbers;
@@ -28,6 +27,7 @@
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.nio.CharBuffer;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
@@ -240,13 +240,12 @@ public final String textOrNull() throws IOException {
         return text();
     }
 
-
     @Override
-    public BytesRef utf8BytesOrNull() throws IOException {
+    public CharBuffer charBufferOrNull() throws IOException {
         if (currentToken() == Token.VALUE_NULL) {
             return null;
         }
-        return utf8Bytes();
+        return charBuffer();
     }
 
     @Override
diff --git a/server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java
index f7334df8e0e84..d1337d5258aa9 100644
--- a/server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java
@@ -37,6 +37,7 @@
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.nio.CharBuffer;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -194,27 +195,31 @@ public final int hashCode() {
     protected abstract int doHashCode();
 
     /**
-     * This helper method checks if the object passed in is a string, if so it
-     * converts it to a {@link BytesRef}.
+     * This helper method checks if the object passed in is a string or {@link CharBuffer},
+     * if so it converts it to a {@link BytesRef}.
      * @param obj the input object
      * @return the same input object or a {@link BytesRef} representation if input was of type string
      */
-    static Object convertToBytesRefIfString(Object obj) {
+    static Object maybeConvertToBytesRef(Object obj) {
         if (obj instanceof String) {
             return BytesRefs.toBytesRef(obj);
+        } else if (obj instanceof CharBuffer) {
+            return new BytesRef((CharBuffer) obj);
         }
         return obj;
     }
 
     /**
-     * This helper method checks if the object passed in is a {@link BytesRef}, if so it
-     * converts it to a utf8 string.
+     * This helper method checks if the object passed in is a {@link BytesRef} or {@link CharBuffer},
+     * if so it converts it to a utf8 string.
      * @param obj the input object
-     * @return the same input object or a utf8 string if input was of type {@link BytesRef}
+     * @return the same input object or a utf8 string if input was of type {@link BytesRef} or {@link CharBuffer}
      */
-    static Object convertToStringIfBytesRef(Object obj) {
+    static Object maybeConvertToString(Object obj) {
         if (obj instanceof BytesRef) {
             return ((BytesRef) obj).utf8ToString();
+        } else if (obj instanceof CharBuffer) {
+            return new BytesRef((CharBuffer) obj).utf8ToString();
         }
         return obj;
     }
diff --git a/server/src/main/java/org/elasticsearch/index/query/BaseTermQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/BaseTermQueryBuilder.java
index d8ca025dafa86..a3ef36204f032 100644
--- a/server/src/main/java/org/elasticsearch/index/query/BaseTermQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/BaseTermQueryBuilder.java
@@ -116,7 +116,7 @@ public BaseTermQueryBuilder(String fieldName, Object value) {
             throw new IllegalArgumentException("value cannot be null");
         }
         this.fieldName = fieldName;
-        this.value = convertToBytesRefIfString(value);
+        this.value = maybeConvertToBytesRef(value);
     }
 
     /**
@@ -144,14 +144,14 @@ public String fieldName() {
      *  If necessary, converts internal {@link BytesRef} representation back to string.
      */
     public Object value() {
-        return convertToStringIfBytesRef(this.value);
+        return maybeConvertToString(this.value);
     }
 
     @Override
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(getName());
         builder.startObject(fieldName);
-        builder.field(VALUE_FIELD.getPreferredName(), convertToStringIfBytesRef(this.value));
+        builder.field(VALUE_FIELD.getPreferredName(), maybeConvertToString(this.value));
         printBoostAndQueryName(builder);
         builder.endObject();
         builder.endObject();
diff --git a/server/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java
index 91843ffbd3c9d..379f583ef6082 100644
--- a/server/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java
@@ -153,7 +153,7 @@ public FuzzyQueryBuilder(String fieldName, Object value) {
             throw new IllegalArgumentException("query value cannot be null");
         }
         this.fieldName = fieldName;
-        this.value = convertToBytesRefIfString(value);
+        this.value = maybeConvertToBytesRef(value);
     }
 
     /**
@@ -186,7 +186,7 @@ public String fieldName() {
     }
 
     public Object value() {
-        return convertToStringIfBytesRef(this.value);
+        return maybeConvertToString(this.value);
     }
 
     public FuzzyQueryBuilder fuzziness(Fuzziness fuzziness) {
@@ -238,7 +238,7 @@ public String rewrite() {
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(NAME);
         builder.startObject(fieldName);
-        builder.field(VALUE_FIELD.getPreferredName(), convertToStringIfBytesRef(this.value));
+        builder.field(VALUE_FIELD.getPreferredName(), maybeConvertToString(this.value));
         fuzziness.toXContent(builder, params);
         builder.field(PREFIX_LENGTH_FIELD.getPreferredName(), prefixLength);
         builder.field(MAX_EXPANSIONS_FIELD.getPreferredName(), maxExpansions);
@@ -274,9 +274,9 @@ public static FuzzyQueryBuilder fromXContent(XContentParser parser) throws IOExc
                         currentFieldName = parser.currentName();
                     } else if (token.isValue()) {
                         if (TERM_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (VALUE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             boost = parser.floatValue();
                         } else if (Fuzziness.FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
@@ -303,7 +303,7 @@ public static FuzzyQueryBuilder fromXContent(XContentParser parser) throws IOExc
             } else {
                 throwParsingExceptionOnMultipleFields(NAME, parser.getTokenLocation(), fieldName, parser.currentName());
                 fieldName = parser.currentName();
-                value = parser.objectBytes();
+                value = maybeConvertToBytesRef(parser.objectBytes());
             }
         }
         return new FuzzyQueryBuilder(fieldName, value)
diff --git a/server/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java
index a94c2dae283a5..d0aa588aeb997 100644
--- a/server/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java
@@ -221,7 +221,7 @@ public Item(@Nullable String index, @Nullable String type, XContentBuilder doc)
             if (in.readBoolean()) {
                 doc = (BytesReference) in.readGenericValue();
                 if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                    xContentType = XContentType.readFrom(in);
+                    xContentType = in.readEnum(XContentType.class);
                 } else {
                     xContentType = XContentFactory.xContentType(doc);
                 }
@@ -243,7 +243,7 @@ public void writeTo(StreamOutput out) throws IOException {
             if (doc != null) {
                 out.writeGenericValue(doc);
                 if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-                    xContentType.writeTo(out);
+                    out.writeEnum(xContentType);
                 }
             } else {
                 out.writeString(id);
diff --git a/server/src/main/java/org/elasticsearch/index/query/RangeQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/RangeQueryBuilder.java
index 9cf008e1b1b2e..48f7f9335ab13 100644
--- a/server/src/main/java/org/elasticsearch/index/query/RangeQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/RangeQueryBuilder.java
@@ -162,7 +162,7 @@ public String fieldName() {
      * of query to be equal regardless of whether it was created from XContent or via Java API.
      */
     public RangeQueryBuilder from(Object from, boolean includeLower) {
-        this.from = convertToBytesRefIfString(from);
+        this.from = maybeConvertToBytesRef(from);
         this.includeLower = includeLower;
         return this;
     }
@@ -178,7 +178,7 @@ public RangeQueryBuilder from(Object from) {
      * Gets the lower range value for this query.
      */
     public Object from() {
-        return convertToStringIfBytesRef(this.from);
+        return maybeConvertToString(this.from);
     }
 
     /**
@@ -199,7 +199,7 @@ public RangeQueryBuilder gte(Object from) {
      * The to part of the range query. Null indicates unbounded.
      */
     public RangeQueryBuilder to(Object to, boolean includeUpper) {
-        this.to = convertToBytesRefIfString(to);
+        this.to = maybeConvertToBytesRef(to);
         this.includeUpper = includeUpper;
         return this;
     }
@@ -218,7 +218,7 @@ public RangeQueryBuilder to(Object to) {
      * of query to be equal regardless of whether it was created from XContent or via Java API.
      */
     public Object to() {
-        return convertToStringIfBytesRef(this.to);
+        return maybeConvertToString(this.to);
     }
 
     /**
@@ -334,8 +334,8 @@ public RangeQueryBuilder relation(String relation) {
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(NAME);
         builder.startObject(fieldName);
-        builder.field(FROM_FIELD.getPreferredName(), convertToStringIfBytesRef(this.from));
-        builder.field(TO_FIELD.getPreferredName(), convertToStringIfBytesRef(this.to));
+        builder.field(FROM_FIELD.getPreferredName(), maybeConvertToString(this.from));
+        builder.field(TO_FIELD.getPreferredName(), maybeConvertToString(this.to));
         builder.field(INCLUDE_LOWER_FIELD.getPreferredName(), includeLower);
         builder.field(INCLUDE_UPPER_FIELD.getPreferredName(), includeUpper);
         if (timeZone != null) {
@@ -377,9 +377,9 @@ public static RangeQueryBuilder fromXContent(XContentParser parser) throws IOExc
                         currentFieldName = parser.currentName();
                     } else {
                         if (FROM_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            from = parser.objectBytes();
+                            from = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (TO_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            to = parser.objectBytes();
+                            to = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (INCLUDE_LOWER_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             includeLower = parser.booleanValue();
                         } else if (INCLUDE_UPPER_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
@@ -387,16 +387,16 @@ public static RangeQueryBuilder fromXContent(XContentParser parser) throws IOExc
                         } else if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             boost = parser.floatValue();
                         } else if (GT_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            from = parser.objectBytes();
+                            from = maybeConvertToBytesRef(parser.objectBytes());
                             includeLower = false;
                         } else if (GTE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            from = parser.objectBytes();
+                            from = maybeConvertToBytesRef(parser.objectBytes());
                             includeLower = true;
                         } else if (LT_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            to = parser.objectBytes();
+                            to = maybeConvertToBytesRef(parser.objectBytes());
                             includeUpper = false;
                         } else if (LTE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            to = parser.objectBytes();
+                            to = maybeConvertToBytesRef(parser.objectBytes());
                             includeUpper = true;
                         } else if (TIME_ZONE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             timeZone = parser.text();
diff --git a/server/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java
index f5b286451863f..0a02ff125d1cf 100644
--- a/server/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/SpanTermQueryBuilder.java
@@ -109,9 +109,9 @@ public static SpanTermQueryBuilder fromXContent(XContentParser parser) throws IO
                         currentFieldName = parser.currentName();
                     } else {
                         if (TERM_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (BaseTermQueryBuilder.VALUE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             boost = parser.floatValue();
                         } else if (AbstractQueryBuilder.NAME_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
@@ -125,7 +125,7 @@ public static SpanTermQueryBuilder fromXContent(XContentParser parser) throws IO
             } else {
                 throwParsingExceptionOnMultipleFields(NAME, parser.getTokenLocation(), fieldName, parser.currentName());
                 fieldName = parser.currentName();
-                value = parser.objectBytes();
+                value = maybeConvertToBytesRef(parser.objectBytes());
             }
         }
 
diff --git a/server/src/main/java/org/elasticsearch/index/query/TermQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/TermQueryBuilder.java
index 0df4973329d36..c35aa9b03d581 100644
--- a/server/src/main/java/org/elasticsearch/index/query/TermQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/TermQueryBuilder.java
@@ -100,9 +100,9 @@ public static TermQueryBuilder fromXContent(XContentParser parser) throws IOExce
                         currentFieldName = parser.currentName();
                     } else {
                         if (TERM_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (VALUE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                            value = parser.objectBytes();
+                            value = maybeConvertToBytesRef(parser.objectBytes());
                         } else if (AbstractQueryBuilder.NAME_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             queryName = parser.text();
                         } else if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
@@ -116,7 +116,7 @@ public static TermQueryBuilder fromXContent(XContentParser parser) throws IOExce
             } else if (token.isValue()) {
                 throwParsingExceptionOnMultipleFields(NAME, parser.getTokenLocation(), fieldName, parser.currentName());
                 fieldName = currentFieldName;
-                value = parser.objectBytes();
+                value = maybeConvertToBytesRef(parser.objectBytes());
             } else if (token == XContentParser.Token.START_ARRAY) {
                 throw new ParsingException(parser.getTokenLocation(), "[term] query does not support array of values");
             }
diff --git a/server/src/main/java/org/elasticsearch/index/query/TermsQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/TermsQueryBuilder.java
index f235c785cb195..a144cbf088a01 100644
--- a/server/src/main/java/org/elasticsearch/index/query/TermsQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/TermsQueryBuilder.java
@@ -44,6 +44,7 @@
 import org.elasticsearch.indices.TermsLookup;
 
 import java.io.IOException;
+import java.nio.CharBuffer;
 import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -234,11 +235,12 @@ private static List<?> convert(Iterable<?> values) {
 
     /**
      * Convert the list in a way that optimizes storage in the case that all
-     * elements are either integers or {@link String}s/{@link BytesRef}s. This
-     * is useful to help garbage collections for use-cases that involve sending
-     * very large terms queries to Elasticsearch. If the list does not only
-     * contain integers or {@link String}s, then a list is returned where all
-     * {@link String}s have been replaced with {@link BytesRef}s.
+     * elements are either integers or {@link String}s/{@link BytesRef}/
+     * {@link CharBuffer}s. This is useful to help garbage collections for
+     * use-cases that involve sending very large terms queries to Elasticsearch.
+     * If the list does not only contain integers or {@link String}s, then a
+     * list is returned where all {@link String}/{@link CharBuffer}s have been
+     * replaced with {@link BytesRef}s.
      */
     static List<?> convert(List<?> list) {
         if (list.isEmpty()) {
@@ -270,6 +272,8 @@ public int size() {
                     BytesRef b;
                     if (o instanceof BytesRef) {
                         b = (BytesRef) o;
+                    } else if (o instanceof CharBuffer) {
+                        b = new BytesRef((CharBuffer) o);
                     } else {
                         builder.copyChars(o.toString());
                         b = builder.get();
@@ -395,7 +399,7 @@ public static TermsQueryBuilder fromXContent(XContentParser parser) throws IOExc
     static List<Object> parseValues(XContentParser parser) throws IOException {
         List<Object> values = new ArrayList<>();
         while (parser.nextToken() != XContentParser.Token.END_ARRAY) {
-            Object value = parser.objectBytes();
+            Object value = maybeConvertToBytesRef(parser.objectBytes());
             if (value == null) {
                 throw new ParsingException(parser.getTokenLocation(), "No value specified for terms query");
             }
diff --git a/server/src/main/java/org/elasticsearch/index/query/TypeQueryBuilder.java b/server/src/main/java/org/elasticsearch/index/query/TypeQueryBuilder.java
index c6df4f59e7eeb..365806ab10c30 100644
--- a/server/src/main/java/org/elasticsearch/index/query/TypeQueryBuilder.java
+++ b/server/src/main/java/org/elasticsearch/index/query/TypeQueryBuilder.java
@@ -22,6 +22,7 @@
 import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -39,16 +40,9 @@ public class TypeQueryBuilder extends AbstractQueryBuilder<TypeQueryBuilder> {
 
     private static final ParseField VALUE_FIELD = new ParseField("value");
 
-    private final BytesRef type;
+    private final String type;
 
     public TypeQueryBuilder(String type) {
-        if (type == null) {
-            throw new IllegalArgumentException("[type] cannot be null");
-        }
-        this.type = BytesRefs.toBytesRef(type);
-    }
-
-    TypeQueryBuilder(BytesRef type) {
         if (type == null) {
             throw new IllegalArgumentException("[type] cannot be null");
         }
@@ -60,28 +54,36 @@ public TypeQueryBuilder(String type) {
      */
     public TypeQueryBuilder(StreamInput in) throws IOException {
         super(in);
-        type = in.readBytesRef();
+        if (in.getVersion().onOrAfter(Version.V_6_3_0)) {
+            type = in.readString();
+        } else {
+            type = in.readBytesRef().utf8ToString();
+        }
     }
 
     @Override
     protected void doWriteTo(StreamOutput out) throws IOException {
-        out.writeBytesRef(type);
+        if (out.getVersion().onOrAfter(Version.V_6_3_0)) {
+            out.writeString(type);
+        } else {
+            out.writeBytesRef(new BytesRef(type));
+        }
     }
 
     public String type() {
-        return BytesRefs.toString(this.type);
+        return type;
     }
 
     @Override
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(NAME);
-        builder.field(VALUE_FIELD.getPreferredName(), type.utf8ToString());
+        builder.field(VALUE_FIELD.getPreferredName(), type);
         printBoostAndQueryName(builder);
         builder.endObject();
     }
 
     public static TypeQueryBuilder fromXContent(XContentParser parser) throws IOException {
-        BytesRef type = null;
+        String type = null;
         String queryName = null;
         float boost = AbstractQueryBuilder.DEFAULT_BOOST;
         String currentFieldName = null;
@@ -95,7 +97,7 @@ public static TypeQueryBuilder fromXContent(XContentParser parser) throws IOExce
                 } else if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                     boost = parser.floatValue();
                 } else if (VALUE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
-                    type = parser.utf8Bytes();
+                    type = parser.text();
                 } else {
                     throw new ParsingException(parser.getTokenLocation(),
                             "[" + TypeQueryBuilder.NAME + "] filter doesn't support [" + currentFieldName + "]");
@@ -124,7 +126,7 @@ public String getWriteableName() {
     @Override
     protected Query doToQuery(QueryShardContext context) throws IOException {
         //LUCENE 4 UPGRADE document mapper should use bytesref as well?
-        DocumentMapper documentMapper = context.getMapperService().documentMapper(type.utf8ToString());
+        DocumentMapper documentMapper = context.getMapperService().documentMapper(type);
         if (documentMapper == null) {
             // no type means no documents
             return new MatchNoDocsQuery();
diff --git a/server/src/main/java/org/elasticsearch/ingest/PipelineConfiguration.java b/server/src/main/java/org/elasticsearch/ingest/PipelineConfiguration.java
index 62e0fae04b30d..3d96493746805 100644
--- a/server/src/main/java/org/elasticsearch/ingest/PipelineConfiguration.java
+++ b/server/src/main/java/org/elasticsearch/ingest/PipelineConfiguration.java
@@ -120,7 +120,7 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
 
     public static PipelineConfiguration readFrom(StreamInput in) throws IOException {
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            return new PipelineConfiguration(in.readString(), in.readBytesReference(), XContentType.readFrom(in));
+            return new PipelineConfiguration(in.readString(), in.readBytesReference(), in.readEnum(XContentType.class));
         } else {
             final String id = in.readString();
             final BytesReference config = in.readBytesReference();
@@ -137,7 +137,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(id);
         out.writeBytesReference(config);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 
diff --git a/server/src/main/java/org/elasticsearch/script/Script.java b/server/src/main/java/org/elasticsearch/script/Script.java
index 53b496ba138d7..7361bd2fc2a71 100644
--- a/server/src/main/java/org/elasticsearch/script/Script.java
+++ b/server/src/main/java/org/elasticsearch/script/Script.java
@@ -507,7 +507,7 @@ public Script(StreamInput in) throws IOException {
 
             if (in.readBoolean()) {
                 this.options = new HashMap<>();
-                XContentType contentType = XContentType.readFrom(in);
+                XContentType contentType = in.readEnum(XContentType.class);
                 this.options.put(CONTENT_TYPE_OPTION, contentType.mediaType());
             } else if (type == ScriptType.INLINE) {
                 options = new HashMap<>();
@@ -571,7 +571,7 @@ public void writeTo(StreamOutput out) throws IOException {
             if (options != null && options.containsKey(CONTENT_TYPE_OPTION)) {
                 XContentType contentType = XContentType.fromMediaTypeOrFormat(options.get(CONTENT_TYPE_OPTION));
                 out.writeBoolean(true);
-                contentType.writeTo(out);
+                out.writeEnum(contentType);
             } else {
                 out.writeBoolean(false);
             }
diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/ParsedSignificantStringTerms.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/ParsedSignificantStringTerms.java
index 008a5a28e5d39..365cc8b588aec 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/ParsedSignificantStringTerms.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/ParsedSignificantStringTerms.java
@@ -25,6 +25,7 @@
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.nio.CharBuffer;
 
 public class ParsedSignificantStringTerms extends ParsedSignificantTerms {
 
@@ -71,7 +72,14 @@ protected XContentBuilder keyToXContent(XContentBuilder builder) throws IOExcept
         }
 
         static ParsedBucket fromXContent(XContentParser parser) throws IOException {
-            return parseSignificantTermsBucketXContent(parser, new ParsedBucket(), (p, bucket) -> bucket.key = p.utf8BytesOrNull());
+            return parseSignificantTermsBucketXContent(parser, new ParsedBucket(), (p, bucket) -> {
+                CharBuffer cb = p.charBufferOrNull();
+                if (cb == null) {
+                    bucket.key = null;
+                } else {
+                    bucket.key = new BytesRef(cb);
+                }
+            });
         }
     }
 }
diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/ParsedStringTerms.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/ParsedStringTerms.java
index 792365d6b1aa2..ecd88c871dfcc 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/ParsedStringTerms.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/ParsedStringTerms.java
@@ -25,6 +25,7 @@
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
+import java.nio.CharBuffer;
 
 public class ParsedStringTerms extends ParsedTerms {
 
@@ -79,7 +80,14 @@ protected XContentBuilder keyToXContent(XContentBuilder builder) throws IOExcept
         }
 
         static ParsedBucket fromXContent(XContentParser parser) throws IOException {
-            return parseTermsBucketXContent(parser, ParsedBucket::new, (p, bucket) -> bucket.key = p.utf8BytesOrNull());
+            return parseTermsBucketXContent(parser, ParsedBucket::new, (p, bucket) -> {
+                    CharBuffer cb = p.charBufferOrNull();
+                    if (cb == null) {
+                        bucket.key = null;
+                    } else {
+                        bucket.key = new BytesRef(cb);
+                    }
+                });
         }
     }
 }
diff --git a/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java b/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
index e395f1688a109..609c12fb6d874 100644
--- a/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
+++ b/server/src/test/java/org/elasticsearch/common/xcontent/BaseXContentTestCase.java
@@ -342,7 +342,7 @@ public void testBinaryUTF8() throws Exception {
         assertSame(parser.nextToken(), Token.FIELD_NAME);
         assertEquals(parser.currentName(), "utf8");
         assertTrue(parser.nextToken().isValue());
-        assertThat(parser.utf8Bytes().utf8ToString(), equalTo(randomBytesRef.utf8ToString()));
+        assertThat(new BytesRef(parser.charBuffer()).utf8ToString(), equalTo(randomBytesRef.utf8ToString()));
         assertSame(parser.nextToken(), Token.END_OBJECT);
         assertNull(parser.nextToken());
     }
@@ -360,7 +360,7 @@ public void testText() throws Exception {
         assertSame(parser.nextToken(), Token.FIELD_NAME);
         assertEquals(parser.currentName(), "text");
         assertTrue(parser.nextToken().isValue());
-        assertThat(parser.utf8Bytes().utf8ToString(), equalTo(random.utf8ToString()));
+        assertThat(new BytesRef(parser.charBuffer()).utf8ToString(), equalTo(random.utf8ToString()));
         assertSame(parser.nextToken(), Token.END_OBJECT);
         assertNull(parser.nextToken());
     }
diff --git a/server/src/test/java/org/elasticsearch/common/xcontent/cbor/CborXContentParserTests.java b/server/src/test/java/org/elasticsearch/common/xcontent/cbor/CborXContentParserTests.java
index 1a66987510152..b95ec03f94c14 100644
--- a/server/src/test/java/org/elasticsearch/common/xcontent/cbor/CborXContentParserTests.java
+++ b/server/src/test/java/org/elasticsearch/common/xcontent/cbor/CborXContentParserTests.java
@@ -35,7 +35,7 @@ public void testEmptyValue() throws IOException {
             // See https://github.com/elastic/elasticsearch/issues/8629
             XContentParser parser = createParser(CborXContent.cborXContent, ref);
             while (parser.nextToken() != null) {
-                parser.utf8Bytes();
+                parser.charBuffer();
             }
         }
     }
diff --git a/server/src/test/java/org/elasticsearch/search/functionscore/QueryRescorerIT.java b/server/src/test/java/org/elasticsearch/search/functionscore/QueryRescorerIT.java
index 9bf7889d1cd0b..98f14c1aa6e74 100644
--- a/server/src/test/java/org/elasticsearch/search/functionscore/QueryRescorerIT.java
+++ b/server/src/test/java/org/elasticsearch/search/functionscore/QueryRescorerIT.java
@@ -754,6 +754,7 @@ public void testRescorePhaseWithInvalidSort() throws Exception {
         }
     }
 
+    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/28932")
     public void testRescoreAfterCollapse() throws Exception {
         assertAcked(prepareCreate("test")
             .addMapping(