diff --git a/modules/reindex/build.gradle b/modules/reindex/build.gradle
index 3a5d93629d455..6f456f533e2b8 100644
--- a/modules/reindex/build.gradle
+++ b/modules/reindex/build.gradle
@@ -163,16 +163,11 @@ if (Os.isFamily(Os.FAMILY_WINDOWS)) {
 
 tasks.named("yamlRestCompatTest").configure {
   systemProperty 'tests.rest.blacklist', [
-    'reindex/20_validation/reindex without source gives useful error message', /* type in exception message */
-    'reindex/85_scripting/Reindex all docs with one doc deletion', /*type in a request*/
-    'delete_by_query/10_basic/Limit by size',
+    /*type related failures */
+    'reindex/20_validation/reindex without source gives useful error message',
+    'reindex/85_scripting/Reindex all docs with one doc deletion',
     'delete_by_query/10_basic/Response for version conflict (seq no powered)',
-    'delete_by_query/20_validation/both max_docs and size fails',
-    'delete_by_query/20_validation/invalid size fails',
-    'update_by_query/10_basic/Limit by size',
     'update_by_query/10_basic/Response for version conflict (seq no powered)',
-    'update_by_query/20_validation/inconsistent max_docs and size fails',
-    'update_by_query/20_validation/invalid size fails',
     'update_by_query/20_validation/update_by_query without source gives useful error message'
   ].join(',')
 }
diff --git a/modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByQueryRestHandler.java b/modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByQueryRestHandler.java
index 682f0f763b6a9..59e6a17711914 100644
--- a/modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByQueryRestHandler.java
+++ b/modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByQueryRestHandler.java
@@ -10,8 +10,10 @@
 
 import org.elasticsearch.action.ActionType;
 import org.elasticsearch.action.search.SearchRequest;
+import org.elasticsearch.common.RestApiVersion;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
+import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -21,6 +23,7 @@
 import java.io.IOException;
 import java.util.Map;
 import java.util.function.Consumer;
+import java.util.function.IntConsumer;
 
 /**
  * Rest handler for reindex actions that accepts a search request like Update-By-Query or Delete-By-Query
@@ -41,7 +44,10 @@ protected void parseInternalRequest(Request internal, RestRequest restRequest, N
         SearchRequest searchRequest = internal.getSearchRequest();
 
         try (XContentParser parser = extractRequestSpecificFields(restRequest, bodyConsumers)) {
-            RestSearchAction.parseSearchRequest(searchRequest, restRequest, parser, namedWriteableRegistry, size -> failOnSizeSpecified());
+            IntConsumer sizeConsumer = restRequest.getRestApiVersion() == RestApiVersion.V_7 ?
+                size -> setMaxDocsFromSearchSize(internal, size) :
+                size -> failOnSizeSpecified();
+            RestSearchAction.parseSearchRequest(searchRequest, restRequest, parser, namedWriteableRegistry, sizeConsumer);
         }
 
         searchRequest.source().size(restRequest.paramAsInt("scroll_size", searchRequest.source().size()));
@@ -87,4 +93,9 @@ private XContentParser extractRequestSpecificFields(RestRequest restRequest,
     private static void failOnSizeSpecified() {
         throw new IllegalArgumentException("invalid parameter [size], use [max_docs] instead");
     }
+
+    private void setMaxDocsFromSearchSize(Request request, int size) {
+        LoggingDeprecationHandler.INSTANCE.logRenamedField(null, null, "size", "max_docs", true);
+        setMaxDocsValidateIdentical(request, size);
+    }
 }