diff --git a/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java b/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
index 47f5ad6..df5d291 100644
--- a/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
+++ b/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
@@ -579,7 +579,7 @@
 
     if ("mergeable".equalsIgnoreCase(value)) {
       if (!args.indexMergeable) {
-        throw new QueryParseException("server does not support 'mergeable'. check configs");
+        throw new QueryParseException("'is:mergeable' operator is not supported by server");
       }
       return new BooleanPredicate(ChangeField.MERGEABLE);
     }
diff --git a/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java b/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
index 962b691..9c12052 100644
--- a/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
+++ b/javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java
@@ -3093,7 +3093,7 @@
     assertThat(thrown.getCause()).isInstanceOf(QueryParseException.class);
     assertThat(thrown)
         .hasMessageThat()
-        .contains("server does not support 'mergeable'. check configs");
+        .contains("'is:mergeable' operator is not supported by server");
   }
 
   protected ChangeInserter newChange(TestRepository<Repo> repo) throws Exception {