diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 1b105ba1c4..4bb33ee03c 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -413,7 +413,7 @@ static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
 static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
 									   Node *def, LOCKMODE lockmode);
 static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
-static void ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recursing);
+static void ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing, LOCKMODE lockmode);
 static ObjectAddress ATExecDropExpression(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName, int16 colNum,
 										 Node *newValue, LOCKMODE lockmode);
@@ -4151,7 +4151,7 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_DropExpression: /* ALTER COLUMN DROP EXPRESSION */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
-			ATPrepDropExpression(rel, cmd, recursing);
+			ATPrepDropExpression(rel, cmd, recurse, recursing, lockmode);
 			pass = AT_PASS_DROP;
 			break;
 		case AT_SetStatistics:	/* ALTER COLUMN SET STATISTICS */
@@ -7262,8 +7262,24 @@ ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE
  * ALTER TABLE ALTER COLUMN DROP EXPRESSION
  */
 static void
-ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recursing)
+ATPrepDropExpression(Relation rel, AlterTableCmd *cmd, bool recurse, bool recursing, LOCKMODE lockmode)
 {
+	/*
+	 * Reject ONLY if there are child tables.  We could implement this, but it
+	 * is a bit complicated.  GENERATED clauses must be attached to the column
+	 * definition and cannot be added later like DEFAULT, so if a child table
+	 * has a generation expression that the parent does not have, the child
+	 * column will necessarily be an attlocal column.  So to implement ONLY
+	 * here, we'd need extra code to update attislocal of the direct child
+	 * tables, somewhat similar to how DROP COLUMN does it, so that the
+	 * resulting state can be properly dumped and restored.
+	 */
+	if (!recurse &&
+		find_inheritance_children(RelationGetRelid(rel), lockmode))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("ALTER TABLE / DROP EXPRESSION must be applied to child tables too")));
+
 	/*
 	 * Cannot drop generation expression from inherited columns.
 	 */
diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated.out
index 7ccc3c65ed..4b06260304 100644
--- a/src/test/regress/expected/generated.out
+++ b/src/test/regress/expected/generated.out
@@ -805,13 +805,14 @@ CREATE TABLE gtest30 (
     b int GENERATED ALWAYS AS (a * 2) STORED
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
-ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;
+ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;  -- error
+ERROR:  ALTER TABLE / DROP EXPRESSION must be applied to child tables too
 \d gtest30
-              Table "public.gtest30"
- Column |  Type   | Collation | Nullable | Default 
---------+---------+-----------+----------+---------
+                            Table "public.gtest30"
+ Column |  Type   | Collation | Nullable |              Default               
+--------+---------+-----------+----------+------------------------------------
  a      | integer |           |          | 
- b      | integer |           |          | 
+ b      | integer |           |          | generated always as (a * 2) stored
 Number of child tables: 1 (Use \d+ to list them.)
 
 \d gtest30_1
diff --git a/src/test/regress/sql/generated.sql b/src/test/regress/sql/generated.sql
index 4cff1279c7..c86ad34b00 100644
--- a/src/test/regress/sql/generated.sql
+++ b/src/test/regress/sql/generated.sql
@@ -411,7 +411,7 @@ CREATE TABLE gtest30 (
     b int GENERATED ALWAYS AS (a * 2) STORED
 );
 CREATE TABLE gtest30_1 () INHERITS (gtest30);
-ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;
+ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION;  -- error
 \d gtest30
 \d gtest30_1
 ALTER TABLE gtest30_1 ALTER COLUMN b DROP EXPRESSION;  -- error