diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b53cd2b68b..f11092d840 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2021-02-03  Pedro Alves  <pedro@palves.net>
+
+	* remote.c (remote_notif_stop_ack): Don't error out on
+	TARGET_WAITKIND_IGNORE; instead, just ignore the notification.
+	(remote_target::discard_pending_stop_replies): Don't delete
+	in-flight notification; instead, clear its contents.
+
 2021-02-03  Pedro Alves  <pedro@palves.net>
 
 	* remote.c (extended_remote_target::attach): Set target async in
diff --git a/gdb/remote.c b/gdb/remote.c
index f183b4f3b0..512bd9467f 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -7006,13 +7006,11 @@ remote_notif_stop_ack (remote_target *remote,
   /* acknowledge */
   putpkt (remote, self->ack_command);
 
-  if (stop_reply->ws.kind == TARGET_WAITKIND_IGNORE)
-    {
-      /* We got an unknown stop reply.  */
-      error (_("Unknown stop reply"));
-    }
-
-  remote->push_stop_reply (stop_reply);
+  /* Kind can be TARGET_WAITKIND_IGNORE if we have meanwhile discarded
+     the notification.  It was left in the queue because we need to
+     acknowledge it and pull the rest of the notifications out.  */
+  if (stop_reply->ws.kind != TARGET_WAITKIND_IGNORE)
+    remote->push_stop_reply (stop_reply);
 }
 
 static int
@@ -7181,8 +7179,14 @@ remote_target::discard_pending_stop_replies (struct inferior *inf)
   /* Discard the in-flight notification.  */
   if (reply != NULL && reply->ptid.pid () == inf->pid)
     {
-      delete reply;
-      rns->pending_event[notif_client_stop.id] = NULL;
+      /* Leave the notification pending, since the server expects that
+	 we acknowledge it with vStopped.  But clear its contents, so
+	 that later on when we acknowledge it, we also discard it.  */
+      reply->ws.kind = TARGET_WAITKIND_IGNORE;
+
+      if (remote_debug)
+	fprintf_unfiltered (gdb_stdlog,
+			    "discarded in-flight notification\n");
     }
 
   /* Discard the stop replies we have already pulled with
diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog
index 2f883e05b5..41154d9e19 100644
--- a/gdbserver/ChangeLog
+++ b/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2021-02-03  Pedro Alves  <pedro@palves.net>
+
+	* server.cc (discard_queued_stop_replies): Don't ever discard the
+	notification at the head of the list.
+
 2021-01-20  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* ax.cc (bytecode_address_table): Make static.
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 77e89fe6ed..a5497e93ce 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -203,6 +203,15 @@ discard_queued_stop_replies (ptid_t ptid)
       next = iter;
       ++next;
 
+      if (iter == notif_stop.queue.begin ())
+	{
+	  /* The head of the list contains the notification that was
+	     already sent to GDB.  So we can't remove it, otherwise
+	     when GDB sends the vStopped, it would ack the _next_
+	     notification, which hadn't been sent yet!  */
+	  continue;
+	}
+
       if (remove_all_on_match_ptid (*iter, ptid))
 	{
 	  delete *iter;