diff --git a/src/bin/pg_upgrade/check.c b/src/bin/pg_upgrade/check.c
index 1b9083597c..0bd2cd0ed1 100644
--- a/src/bin/pg_upgrade/check.c
+++ b/src/bin/pg_upgrade/check.c
@@ -26,6 +26,7 @@ static void check_for_isn_and_int8_passing_mismatch(ClusterInfo *cluster);
 static void check_for_reg_data_type_usage(ClusterInfo *cluster);
 static void check_for_jsonb_9_4_usage(ClusterInfo *cluster);
 static void check_for_pg_role_prefix(ClusterInfo *cluster);
+static void check_for_not_null_inheritance(ClusterInfo *cluster);
 static char *get_canonical_locale_name(int category, const char *locale);
 
 
@@ -99,6 +100,7 @@ check_and_dump_old_cluster(bool live_check)
 	check_for_prepared_transactions(&old_cluster);
 	check_for_reg_data_type_usage(&old_cluster);
 	check_for_isn_and_int8_passing_mismatch(&old_cluster);
+	check_for_not_null_inheritance(&old_cluster);
 
 	/*
 	 * Pre-PG 10 allowed tables with 'unknown' type columns and non WAL logged
@@ -1096,6 +1098,105 @@ check_for_pg_role_prefix(ClusterInfo *cluster)
 	check_ok();
 }
 
+/*
+ * check_for_not_null_inheritance()
+ *
+ *  Currently pg_upgrade will fail if there are any inconsistencies in NOT NULL
+ *  constraint inheritance: In PostgreSQL, we can have a column that is NOT NULL
+ *  in parent, but nullable in its children. So check for inconsistent NOT NULL
+ *  constraints in inheritance tree.
+ */
+static void
+check_for_not_null_inheritance(ClusterInfo *cluster)
+{
+	int			dbnum;
+	FILE	   *script = NULL;
+	bool		found = false;
+	char		output_path[MAXPGPATH];
+
+	prep_status("Checking for NOT NULL inconsistencies in inheritance");
+
+	snprintf(output_path, sizeof(output_path), "not_null_inconsistent_columns.txt");
+
+	for (dbnum = 0; dbnum < cluster->dbarr.ndbs; dbnum++)
+	{
+		PGresult   *res;
+		bool		db_used = false;
+		int			ntups;
+		int			rowno;
+		int			i_nspname,
+					i_relname,
+					i_attname;
+		DbInfo	   *active_db = &cluster->dbarr.dbs[dbnum];
+		PGconn	   *conn = connectToServer(cluster, active_db->db_name);
+
+		res = executeQueryOrDie(conn,
+								"WITH RECURSIVE parents AS ( "
+								"	SELECT	i.inhrelid, i.inhparent "
+								"	FROM	pg_catalog.pg_inherits i "
+								"	UNION ALL "
+								"	SELECT	p.inhrelid, i.inhparent "
+								"   FROM	parents p "
+								"	JOIN	pg_catalog.pg_inherits i "
+								"		ON	i.inhrelid = p.inhparent "
+								") "
+								"SELECT	n.nspname, c.relname, ac.attname  "
+								"FROM	parents p, "
+								"		pg_catalog.pg_attribute ac, "
+								"		pg_catalog.pg_attribute ap, "
+								"		pg_catalog.pg_class c, "
+								"		pg_catalog.pg_namespace n "
+								"WHERE	NOT ac.attnotnull AND "
+								"		ac.attrelid = p.inhrelid AND "
+								"		ap.attrelid = p.inhparent AND "
+								"		ac.attname = ap.attname AND "
+								"		ap.attnotnull AND "
+								"		c.oid = ac.attrelid AND "
+								"		c.relnamespace = n.oid");
+
+		ntups = PQntuples(res);
+		i_nspname = PQfnumber(res, "nspname");
+		i_relname = PQfnumber(res, "relname");
+		i_attname = PQfnumber(res, "attname");
+		for (rowno = 0; rowno < ntups; rowno++)
+		{
+			found = true;
+			if (script == NULL && (script = fopen_priv(output_path, "w")) == NULL)
+				pg_fatal("could not open file \"%s\": %s\n", output_path,
+						 strerror(errno));
+			if (!db_used)
+			{
+				fprintf(script, "Database: %s\n", active_db->db_name);
+				db_used = true;
+			}
+			fprintf(script, "  %s.%s.%s\n",
+					PQgetvalue(res, rowno, i_nspname),
+					PQgetvalue(res, rowno, i_relname),
+					PQgetvalue(res, rowno, i_attname));
+		}
+
+		PQclear(res);
+
+		PQfinish(conn);
+	}
+
+	if (script)
+		fclose(script);
+
+	if (found)
+	{
+		pg_log(PG_REPORT, "fatal\n");
+		pg_fatal("Your installation contains has inconsistencies in NOT NULL\n"
+				 "constraint inheritance: child column is not marked NOT NULL\n"
+				 "while parent column has NOT NULL constraint. You can fix the\n"
+				 "inconsistency by adding NOT NULL constraint and restarting the\n"
+				 "upgrade.\n"
+				 "A list of the problematic columns is in the file:\n"
+				 "    %s\n\n", output_path);
+	}
+	else
+		check_ok();
+}
 
 /*
  * get_canonical_locale_name