diff --git a/Source/BugsnagCrashReport.m b/Source/BugsnagCrashReport.m
index 77c512763..9b49319dc 100644
--- a/Source/BugsnagCrashReport.m
+++ b/Source/BugsnagCrashReport.m
@@ -384,7 +384,7 @@ - (void)addAttribute:(NSString *)attributeName
        toTabWithName:(NSString *)tabName {
     NSMutableDictionary *allMetadata = [self.metaData mutableCopy];
     NSMutableDictionary *allTabData =
-        allMetadata[tabName] ?: [NSMutableDictionary new];
+        [allMetadata[tabName] mutableCopy] ?: [NSMutableDictionary new];
     if (value) {
         id cleanedValue = BSGSanitizeObject(value);
         if (!cleanedValue) {
diff --git a/Source/BugsnagSink.m b/Source/BugsnagSink.m
index f81920713..42902e3bc 100644
--- a/Source/BugsnagSink.m
+++ b/Source/BugsnagSink.m
@@ -26,6 +26,7 @@
 
 #import "BugsnagSink.h"
 #import "Bugsnag.h"
+#import "BugsnagLogger.h"
 #import "BugsnagCollections.h"
 #import "BugsnagNotifier.h"
 #import "BugsnagKeys.h"
@@ -101,9 +102,13 @@ - (void)filterReports:(NSDictionary <NSString *, NSDictionary *> *)reports
             continue;
         BOOL shouldSend = YES;
         for (BugsnagBeforeSendBlock block in configuration.beforeSendBlocks) {
-            shouldSend = block(report, bugsnagReport);
-            if (!shouldSend)
-                break;
+            @try {
+                shouldSend = block(report, bugsnagReport);
+                if (!shouldSend)
+                    break;
+            } @catch (NSException *exception) {
+                bsg_log_err(@"Error from beforeSend callback: %@", exception);
+            }
         }
         if (shouldSend) {
             [bugsnagReports addObject:bugsnagReport];
diff --git a/Tests/BugsnagCrashReportTests.m b/Tests/BugsnagCrashReportTests.m
index e8eda5643..e3df0dcfb 100644
--- a/Tests/BugsnagCrashReportTests.m
+++ b/Tests/BugsnagCrashReportTests.m
@@ -460,4 +460,14 @@ - (void)testAppVersionOverride {
     XCTAssertEqualObjects(@"1.2.3", dictionary[@"app"][@"version"]);
 }
 
+- (void)testReportAddAttr {
+    BugsnagCrashReport *report = [[BugsnagCrashReport alloc] initWithKSReport:@{@"user.metaData": @{@"user": @{@"id": @"user id"}}}];
+    [report addAttribute:@"foo" withValue:@"bar" toTabWithName:@"user"];
+}
+
+- (void)testReportAddMetadata {
+    BugsnagCrashReport *report = [[BugsnagCrashReport alloc] initWithKSReport:@{@"user.metaData": @{@"user": @{@"id": @"user id"}}}];
+    [report addMetadata:@{@"foo": @"bar"} toTabWithName:@"user"];
+}
+
 @end