diff --git a/src/dsql/ExprNodes.cpp b/src/dsql/ExprNodes.cpp
index 12db93d945..519858bd0d 100644
--- a/src/dsql/ExprNodes.cpp
+++ b/src/dsql/ExprNodes.cpp
@@ -3560,10 +3560,7 @@ dsc* CastNode::execute(thread_db* tdbb, jrd_req* request) const
 	if (!value)
 		return NULL;
 
-	if (DTYPE_IS_BLOB(value->dsc_dtype) || DTYPE_IS_BLOB(impure->vlu_desc.dsc_dtype))
-		blb::move(tdbb, value, &impure->vlu_desc);
-	else
-		MOV_move(tdbb, value, &impure->vlu_desc);
+	MOV_move(tdbb, value, &impure->vlu_desc);
 
 	if (impure->vlu_desc.dsc_dtype == dtype_text)
 		INTL_adjust_text_descriptor(tdbb, &impure->vlu_desc);
diff --git a/src/jrd/exe.cpp b/src/jrd/exe.cpp
index 66d5aa44a9..8f899e24b5 100644
--- a/src/jrd/exe.cpp
+++ b/src/jrd/exe.cpp
@@ -395,7 +395,7 @@ void EXE_assignment(thread_db* tdbb, const ValueExprNode* to, dsc* from_desc, bo
 		if (DTYPE_IS_BLOB_OR_QUAD(from_desc->dsc_dtype) || DTYPE_IS_BLOB_OR_QUAD(to_desc->dsc_dtype))
 		{
 			// ASF: Don't let MOV_move call blb::move because MOV
-			// will not pass the destination field to blb::_move.
+			// will not pass the destination field to blb::move.
 
 			record_param* rpb = NULL;
 			USHORT fieldId = 0;
diff --git a/src/jrd/vio.cpp b/src/jrd/vio.cpp
index 63d6a5ad55..a43e6eb7ef 100644
--- a/src/jrd/vio.cpp
+++ b/src/jrd/vio.cpp
@@ -1257,6 +1257,15 @@ void VIO_copy_record(thread_db* tdbb, record_param* org_rpb, record_param* new_r
 	Record* const new_record = new_rpb->rpb_record;
 	fb_assert(org_record && new_record);
 
+	// dimitr:	Clear the req_null flag that may stay active after the last
+	//			boolean evaluation. Here we use only EVL_field() calls that
+	//			do not touch this flag and data copying is done only for
+	//			non-NULL fields, so req_null should never be seen inside blb::move().
+	//			See CORE-6090 for details.
+
+	jrd_req* const request = tdbb->getRequest();
+	request->req_flags &= ~req_null;
+
 	// Copy the original record to the new record. If the format hasn't changed,
 	// this is a simple move. If the format has changed, each field must be
 	// fetched and moved separately, remembering to set the missing flag.
@@ -1275,8 +1284,18 @@ void VIO_copy_record(thread_db* tdbb, record_param* org_rpb, record_param* new_r
 			{
 				if (EVL_field(org_rpb->rpb_relation, org_record, i, &org_desc))
 				{
-					if (DTYPE_IS_BLOB_OR_QUAD(org_desc.dsc_dtype) || DTYPE_IS_BLOB_OR_QUAD(new_desc.dsc_dtype))
-						Jrd::blb::move(tdbb, &org_desc, &new_desc, new_rpb, i);
+					// If the source is not a blob or it's a temporary blob,
+					// then we'll need to materialize the resulting blob.
+					// Thus blb::move() is called with rpb and field ID.
+					// See also CORE-5600.
+
+					const bool materialize =
+						(DTYPE_IS_BLOB_OR_QUAD(new_desc.dsc_dtype) &&
+							!(DTYPE_IS_BLOB_OR_QUAD(org_desc.dsc_dtype) &&
+								((bid*) org_desc.dsc_address)->bid_internal.bid_relation_id));
+
+					if (materialize)
+						blb::move(tdbb, &org_desc, &new_desc, new_rpb, i);
 					else
 						MOV_move(tdbb, &org_desc, &new_desc);
 				}