sync: failed to fetch block hash for height ####: block not found

[JoeGruffins]

This seems to be a random sync error. Its been around forever but I don't see an issue for it. The particular block seems to differ, but sync will get stuck with this error and never fix itself, even restarting:

[ERR] BTCW: Unable to synchronize wallet to chain, trying again in 5s: unable to perform wallet recovery: failed to store sync information 000000000000000000007101d8cb8f46c7c17c7c12f873eb0f717d8751628c08: failed to fetch block hash for height 858852: block not found

The block exists but is reported as block 858,853 here, so I guess its not finding the parent block hash? https://www.blockchain.com/explorer/blocks/btc/000000000000000000007101d8cb8f46c7c17c7c12f873eb0f717d8751628c08

[JoeGruffins]

By checking the birthday I got past the birthday block, but it got stuck again at a later block, so may be something else.

2025-02-25 17:16:30.094 [INF] BTCW: RECOVERY MODE ENABLED -- rescanning for used addresses with recovery_window=250
2025-02-25 17:16:30.101 [INF] BTCW: Seed birthday surpassed, starting recovery of wallet from height=870853 hash=00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc with recovery-window=250
2025-02-25 17:16:30.107 [ERR] BTCW: Unable to synchronize wallet to chain, trying again in 5s: unable to perform wallet recovery: failed to store sync information 00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc: failed to fetch block hash for height 870852: block not found
2025-02-25 17:16:36.108 [INF] BTCW: RECOVERY MODE ENABLED -- rescanning for used addresses with recovery_window=250
2025-02-25 17:16:36.115 [INF] BTCW: Seed birthday surpassed, starting recovery of wallet from height=870853 hash=00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc with recovery-window=250
2025-02-25 17:16:36.122 [ERR] BTCW: Unable to synchronize wallet to chain, trying again in 5s: unable to perform wallet recovery: failed to store sync information 00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc: failed to fetch block hash for height 870852: block not found

There's a suspicious error before this second spat starts. did not get response before timeout:

2025-02-25 17:14:12.820 [DBG] NTRNO: Received feefilter from 174.29.113.87:8333 (outbound)
2025-02-25 17:14:15.801 [WRN] CHAIN: Query(46) from peer 77.174.133.117:8333 failed, rescheduling: did not get response before timeout
2025-02-25 17:14:15.801 [WRN] CHAIN: Query(46) failed with error: did not get response before timeout. Timing out.
2025-02-25 17:14:15.801 [WRN] CHAIN: Batch 46 timed out
2025-02-25 17:14:15.801 [WRN] CHAIN: Query(46) result from peer 85.145.25.166:8333 discarded with retries 4, because batch already canceled: job canceled
2025-02-25 17:14:15.801 [ERR] BTCW: Unable to synchronize wallet to chain, trying again in 5s: unable to perform wallet recovery: did not get response before timeout
2025-02-25 17:14:16.215 [DBG] NTRNO: Received block (hash 000000000000000000027a92dbc32287327219206342ed389276985acbea337e, ver 848683008, 2162 tx, 2024-11-06 18:35:07 +0900 JST) from 77.174.133.117:8333 (outbound)
2025-02-25 17:14:21.802 [INF] BTCW: RECOVERY MODE ENABLED -- rescanning for used addresses with recovery_window=250
2025-02-25 17:14:21.810 [INF] BTCW: Seed birthday surpassed, starting recovery of wallet from height=870853 hash=00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc with recovery-window=250
2025-02-25 17:14:21.817 [ERR] BTCW: Unable to synchronize wallet to chain, trying again in 5s: unable to perform wallet recovery: failed to store sync information 00000000000000000000b9e6cc0b5be06c02f56506fee5c7897edf6cafc4e7cc: failed to fetch block hash for height 870852: block not found

[JoeGruffins]

I think recovery needs a rollback like here

btcwallet/wallet/wallet.go

Line 481 in 311812f

rollbackStamp := w.Manager.SyncedTo()