diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index 22a61dca65d..36bb20a1f6e 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -1341,6 +1341,12 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data,
 
 				RemoveSubscriptionRel(sub->oid, relid);
 
+				/*
+				 * A sequence sync worker may already be running with this
+				 * sequence in its to-do list. It does not have to be stopped.
+				 * It notices that the sequence is no longer part of the
+				 * subscription and skips it, see copy_sequence().
+				 */
 				ereport(DEBUG1,
 						errmsg_internal("sequence \"%s.%s\" removed from subscription \"%s\"",
 										get_namespace_name(get_rel_namespace(relid)),
diff --git a/src/backend/replication/logical/sequencesync.c b/src/backend/replication/logical/sequencesync.c
index 6d551d45791..edd9b24ed3f 100644
--- a/src/backend/replication/logical/sequencesync.c
+++ b/src/backend/replication/logical/sequencesync.c
@@ -60,6 +60,7 @@
 #include "postmaster/interrupt.h"
 #include "replication/logicalworker.h"
 #include "replication/worker_internal.h"
+#include "storage/lmgr.h"
 #include "storage/lwlock.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
@@ -80,7 +81,8 @@ typedef enum CopySeqResult
 	COPYSEQ_MISMATCH,
 	COPYSEQ_SUBSCRIBER_INSUFFICIENT_PERM,
 	COPYSEQ_PUBLISHER_INSUFFICIENT_PERM,
-	COPYSEQ_SKIPPED
+	COPYSEQ_SKIPPED,
+	COPYSEQ_NOT_SUBSCRIBED
 } CopySeqResult;
 
 static List *seqinfos = NIL;
@@ -403,6 +405,29 @@ copy_sequence(LogicalRepSequenceInfo *seqinfo, Oid seqowner)
 	AclResult	aclresult;
 	bool		run_as_owner = MySubscription->runasowner;
 	Oid			seqoid = seqinfo->localrelid;
+	Relation	rel;
+
+	/*
+	 * Take the subscription object lock before checking whether this sequence
+	 * is still part of the subscription. The lock is held until the end of
+	 * the transaction, so the check and the state update below are protected
+	 * from a concurrent ALTER SUBSCRIPTION ... REFRESH PUBLICATION.
+	 *
+	 * AlterSubscription() takes this lock in AccessExclusiveLock mode while
+	 * removing pg_subscription_rel rows, so the row cannot be removed between
+	 * the check and the state update.
+	 */
+	LockSharedObject(SubscriptionRelationId, MySubscription->oid, 0,
+					 AccessShareLock);
+
+	/*
+	 * The sequence may no longer be part of the subscription, in which case
+	 * there is nothing to synchronize and the caller just skips it.
+	 */
+	if (!SearchSysCacheExists2(SUBSCRIPTIONRELMAP,
+							   ObjectIdGetDatum(seqoid),
+							   ObjectIdGetDatum(MySubscription->oid)))
+		return COPYSEQ_NOT_SUBSCRIBED;
 
 	/*
 	 * If the user did not opt to run as the owner of the subscription
@@ -434,12 +459,18 @@ copy_sequence(LogicalRepSequenceInfo *seqinfo, Oid seqowner)
 	if (!run_as_owner)
 		RestoreUserContext(&ucxt);
 
+	rel = table_open(SubscriptionRelRelationId, RowExclusiveLock);
+
 	/*
 	 * Record the remote sequence's LSN in pg_subscription_rel and mark the
-	 * sequence as READY.
+	 * sequence as READY. Both locks it needs are held already, the object
+	 * lock from further up and the relation lock just taken, so say so rather
+	 * than have it take and release them again.
 	 */
 	UpdateSubscriptionRelState(MySubscription->oid, seqoid, SUBREL_STATE_READY,
-							   seqinfo->page_lsn, false);
+							   seqinfo->page_lsn, true);
+
+	table_close(rel, NoLock);
 
 	return COPYSEQ_SUCCESS;
 }
@@ -655,6 +686,19 @@ copy_sequences(WalReceiverConn *conn)
 						batch_skipped_count++;
 					}
 					break;
+				case COPYSEQ_NOT_SUBSCRIBED:
+
+					/*
+					 * A concurrent refresh removed this sequence from the
+					 * subscription. Skipping it is the only sensible action,
+					 * and it must not be treated as an error.
+					 */
+					ereport(LOG,
+							errmsg("skip synchronization of sequence \"%s.%s\" because it is no longer part of subscription \"%s\"",
+								   seqinfo->nspname, seqinfo->seqname,
+								   MySubscription->name));
+					batch_skipped_count++;
+					break;
 			}
 
 			if (sequence_rel)