diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index f9811b6d3c2c8..0f4901b614c2f 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -2032,13 +2032,6 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
 			leftsib = opaque->btpo_next;
 			_bt_relbuf(rel, lbuf);
 
-			/*
-			 * It'd be good to check for interrupts here, but it's not easy to
-			 * do so because a lock is always held. This block isn't
-			 * frequently reached, so hopefully the consequences of not
-			 * checking interrupts aren't too bad.
-			 */
-
 			if (leftsib == P_NONE)
 			{
 				elog(LOG, "no left sibling (concurrent deletion?) of block %u in \"%s\"",
@@ -2057,6 +2050,9 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
 				}
 				return false;
 			}
+
+			CHECK_FOR_INTERRUPTS();
+
 			lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
 			page = BufferGetPage(lbuf);
 			opaque = (BTPageOpaque) PageGetSpecialPointer(page);
@@ -2118,13 +2114,40 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
 	rbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
 	page = BufferGetPage(rbuf);
 	opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+
+	/*
+	 * Validate target's right sibling page.  Its left link must point back to
+	 * the target page.
+	 */
 	if (opaque->btpo_prev != target)
-		ereport(ERROR,
+	{
+		/*
+		 * This is known to fail in the field; sibling link corruption is
+		 * relatively common.  Press on with vacuuming rather than just
+		 * throwing an ERROR (same approach used for left-sibling's-right-link
+		 * validation check a moment ago).
+		 */
+		ereport(LOG,
 				(errcode(ERRCODE_INDEX_CORRUPTED),
 				 errmsg_internal("right sibling's left-link doesn't match: "
-								 "block %u links to %u instead of expected %u in index \"%s\"",
-								 rightsib, opaque->btpo_prev, target,
-								 RelationGetRelationName(rel))));
+								 "right sibling %u of target %u with leafblkno %u "
+								 "and scanblkno %u spuriously links to non-target %u "
+								 "on level %u of index \"%s\"",
+								 rightsib, target, leafblkno,
+								 scanblkno, opaque->btpo_prev,
+								 targetlevel, RelationGetRelationName(rel))));
+
+		/* Must release all pins and locks on failure exit */
+		if (BufferIsValid(lbuf))
+			_bt_relbuf(rel, lbuf);
+		_bt_relbuf(rel, rbuf);
+		_bt_relbuf(rel, buf);
+		if (target != leafblkno)
+			_bt_relbuf(rel, leafbuf);
+
+		return false;
+	}
+
 	rightsib_is_rightmost = P_RIGHTMOST(opaque);
 	*rightsib_empty = (P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
 
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index e8c87e1edf2b4..73cdd52f08005 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -1141,8 +1141,7 @@ btvacuumpage(BTVacState *vstate, BlockNumber scanblkno)
 		 * can't be half-dead because only an interrupted VACUUM process can
 		 * leave pages in that state, so we'd definitely have dealt with it
 		 * back when the page was the scanblkno page (half-dead pages are
-		 * always marked fully deleted by _bt_pagedel()).  This assumes that
-		 * there can be only one vacuum process running at a time.
+		 * always marked fully deleted by _bt_pagedel(), barring corruption).
 		 */
 		if (!opaque || !P_ISLEAF(opaque) || P_ISHALFDEAD(opaque))
 		{