I have troubles with sync on the testnet:
Potential stale tip detected, will try using extra outbound peer (last tip update: 63720 seconds ago)
New outbound peer connected: version: 70016, blocks=2350252, peer=512 (full-relay)
Potential stale tip detected, will try using extra outbound peer (last tip update: 63540 seconds ago)
New outbound peer connected: version: 70016, blocks=2350252, peer=511 (full-relay)
New outbound peer connected: version: 70016, blocks=2350252, peer=509 (block-relay)
Timeout downloading headers from peer=436, disconnecting
I am having the same issue after updating litecoin core to V0.2.21
2022-05-30T13:05:56Z Potential stale tip detected, will try using extra outbound peer (last tip update: 43203 seconds ago)
2022-05-30T13:06:40Z Timeout downloading headers from peer=346, disconnecting
2022-05-30T13:07:06Z New outbound peer connected: version: 70016, blocks=2266096, peer=359 (full-relay)
2022-05-30T13:08:56Z Potential stale tip detected, will try using extra outbound peer (last tip update: 43383 seconds ago)
2022-05-30T13:10:22Z New outbound peer connected: version: 70016, blocks=2272084, peer=360 (full-relay)
2022-05-30T13:11:56Z Potential stale tip detected, will try using extra outbound peer (last tip update: 43563 seconds ago)
2022-05-30T13:14:26Z ERROR: AcceptBlockHeader: block d452a7d492866d1e2546f42b9f75d706e8bfedc0a29d96fdec7a9375af249aee is marked invalid
2022-05-30T13:14:26Z Disconnecting and discouraging peer 360!
2022-05-30T13:14:56Z Potential stale tip detected, will try using extra outbound peer (last tip update: 43743 seconds ago)
2022-05-30T13:17:56Z Potential stale tip detected, will try using extra outbound peer (last tip update: 43923 seconds ago)
After some research I resolved the issue - you need to run a liteconid -reindex command or start syncing from a scratch.
-reindex did not help for me and -zapwallettxes was removed,m any suggestion?