diff --git a/src/backend/commands/publicationcmds.c b/src/backend/commands/publicationcmds.c
index 0f9790c4c0f..24a4d81588c 100644
--- a/src/backend/commands/publicationcmds.c
+++ b/src/backend/commands/publicationcmds.c
@@ -2095,15 +2095,8 @@ AlterPublicationSchemaExceptTables(AlterPublicationStmt *stmt,
 	if (schemaidlist == NIL && !is_schema_publication(pubid))
 		return;
 
-	/*
-	 * Dropping a schema from a publication removes all its EXCEPT entries via
-	 * cascade. The concept of "drop all schema tables from the publication
-	 * EXCEPT these ones" is not supported.
-	 */
-	if (stmt->action == AP_DropObjects)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("EXCEPT clause is not supported with DROP in ALTER PUBLICATION")));
+	/* DROP takes no EXCEPT clause; preprocess_pubobj_list() rejects that */
+	Assert(stmt->action != AP_DropObjects);
 
 	if (stmt->action == AP_AddObjects)
 	{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 14520a5ccab..f20efde5f85 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -207,7 +207,7 @@ static void preprocess_pub_all_objtype_list(List *all_objects_list,
 											bool *all_tables,
 											bool *all_sequences,
 											core_yyscan_t yyscanner);
-static void preprocess_pubobj_list(List *pubobjspec_list,
+static void preprocess_pubobj_list(List *pubobjspec_list, bool allow_except,
 								   core_yyscan_t yyscanner);
 static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
@@ -11315,7 +11315,7 @@ CreatePublicationStmt:
 					n->pubname = $3;
 					n->options = $6;
 					n->pubobjects = (List *) $5;
-					preprocess_pubobj_list(n->pubobjects, yyscanner);
+					preprocess_pubobj_list(n->pubobjects, true, yyscanner);
 					$$ = (Node *) n;
 				}
 		;
@@ -11506,7 +11506,7 @@ AlterPublicationStmt:
 
 					n->pubname = $3;
 					n->pubobjects = $5;
-					preprocess_pubobj_list(n->pubobjects, yyscanner);
+					preprocess_pubobj_list(n->pubobjects, true, yyscanner);
 					n->action = AP_AddObjects;
 					n->for_all_tables = false;
 					$$ = (Node *) n;
@@ -11517,7 +11517,7 @@ AlterPublicationStmt:
 
 					n->pubname = $3;
 					n->pubobjects = $5;
-					preprocess_pubobj_list(n->pubobjects, yyscanner);
+					preprocess_pubobj_list(n->pubobjects, true, yyscanner);
 					n->action = AP_SetObjects;
 					n->for_all_tables = false;
 					$$ = (Node *) n;
@@ -11540,7 +11540,7 @@ AlterPublicationStmt:
 
 					n->pubname = $3;
 					n->pubobjects = $5;
-					preprocess_pubobj_list(n->pubobjects, yyscanner);
+					preprocess_pubobj_list(n->pubobjects, false, yyscanner);
 					n->action = AP_DropObjects;
 					n->for_all_tables = false;
 					$$ = (Node *) n;
@@ -20879,7 +20879,8 @@ preprocess_pub_all_objtype_list(List *all_objects_list, List **pubobjects,
  * output list once the schema OID is known.
  */
 static void
-preprocess_pubobj_list(List *pubobjspec_list, core_yyscan_t yyscanner)
+preprocess_pubobj_list(List *pubobjspec_list, bool allow_except,
+					   core_yyscan_t yyscanner)
 {
 	ListCell   *cell;
 	PublicationObjSpec *pubobj;
@@ -20903,6 +20904,18 @@ preprocess_pubobj_list(List *pubobjspec_list, core_yyscan_t yyscanner)
 		if (pubobj->pubobjtype == PUBLICATIONOBJ_CONTINUATION)
 			pubobj->pubobjtype = prevobjtype;
 
+		/*
+		 * Dropping a schema from a publication removes all of its EXCEPT
+		 * entries along with it.  The concept of "drop all schema tables from
+		 * the publication EXCEPT these ones" is not supported, so DROP takes
+		 * no EXCEPT clause.
+		 */
+		if (!allow_except && pubobj->except_tables != NIL)
+			ereport(ERROR,
+					errcode(ERRCODE_SYNTAX_ERROR),
+					errmsg("EXCEPT clause is not supported with DROP in ALTER PUBLICATION"),
+					parser_errposition(pubobj->location));
+
 		if (pubobj->pubobjtype == PUBLICATIONOBJ_TABLE)
 		{
 			/* EXCEPT is not valid for table objects */