diff --git a/src/Series.cpp b/src/Series.cpp
index f8728fff15..b5833aecda 100644
--- a/src/Series.cpp
+++ b/src/Series.cpp
@@ -2755,6 +2755,8 @@ Snapshots Series::snapshots()
 
             break;
         case Access::READ_WRITE:
+            throw std::runtime_error(
+                "[Series::snapshots()] Unimplemented for READ_WRITE mode.");
         case Access::CREATE:
         case Access::APPEND:
             // @todo: properly distinguish here
diff --git a/src/snapshots/ContainerImpls.cpp b/src/snapshots/ContainerImpls.cpp
index 7e625bd1a4..480c11b660 100644
--- a/src/snapshots/ContainerImpls.cpp
+++ b/src/snapshots/ContainerImpls.cpp
@@ -152,6 +152,12 @@ auto StatefulSnapshotsContainer::operator[](key_type const &key)
     auto access = s.series.IOHandler()->m_frontendAccess;
 
     // @todo distinguish read_write
+    if (access == Access::READ_WRITE)
+    {
+        throw std::runtime_error(
+            "[StatefulSnapshotsContainer::operator[]()] Unimplemented for "
+            "READ_WRITE mode.");
+    }
     if (access::write(access))
     {
         auto lastIteration = base_iterator->peekCurrentlyOpenIteration();