diff --git a/src/backend/optimizer/util/inherit.c b/src/backend/optimizer/util/inherit.c
index f9d3ff1e7ac..f9a8bc5cd8f 100644
--- a/src/backend/optimizer/util/inherit.c
+++ b/src/backend/optimizer/util/inherit.c
@@ -386,8 +386,17 @@ expand_partitioned_rtentry(PlannerInfo *root, RelOptInfo *relinfo,
 		Index		childRTindex;
 		RelOptInfo *childrelinfo;
 
-		/* Open rel, acquiring required locks */
-		childrel = table_open(childOID, lockmode);
+		/*
+		 * Open rel, acquiring required locks.  If a partition was recently
+		 * detached and subsequently dropped, then opening it will fail.  In
+		 * this case, behave as though the partition had been pruned.
+		 */
+		childrel = try_table_open(childOID, lockmode);
+		if (childrel == NULL)
+		{
+			relinfo->live_parts = bms_del_member(relinfo->live_parts, i);
+			continue;
+		}
 
 		/*
 		 * Temporary partitions belonging to other sessions should have been