Transaction not spendable

[jholdstock]

I own the address TsiYnTiBdVshdDTMi4P88v4WrHUUDv3Updx which I have used for mining on testnet. Occasionally I will receive transactions which I am then unable to spend.

For example, dc98c495538d5c2b412da8265a83134746c74529db553ab7f78e8df1440b4360 pays to my address, and I see a dcrwallet log line indicating so:

2020-05-12 14:54:30.126 [DBG] WLLT: Marking transaction dc98c495538d5c2b412da8265a83134746c74529db553ab7f78e8df1440b4360 output 2 (1.93182412 DCR) spendable

However, upon an attempt to spend the output ~20 minutes later I get:

2020-05-12 15:16:05.152 [ERR] GRPC: Unary method /walletrpc.WalletService/SignTransaction invoked by 127.0.0.1:33952 errored: rpc error: code = Unknown desc = wallet.SignTransaction: dc98c495538d5c2b412da8265a83134746c74529db553ab7f78e8df1440b4360:2 not found

The wallet was running non-stop throughout this period. The outputs received in transactions immediately before this one, and immediately after this one, are both spendable.

Providing the full log for this time period here: https://pastebin.com/TxZTNJ8b. It may be note-worthy that the log line indicating the output is spendable actually appeared twice, apparently due to a re-org.

Transaction is not returned when querying the wallet with dcrctl:

$ dcrctl --wallet gettransaction dc98c495538d5c2b412da8265a83134746c74529db553ab7f78e8df1440b4360
-5: no information for transaction

The above behaviour was seen on dcrwallet release 1.5.1, built from source locally. The issue is resolved by a wallet rescan - the transaction can be retrieved using gettransaction and the output becomes spendable.

[jrick]

This is an issue with our reorg handling under the rpc syncer (the syncers themselves are responsible with providing the relevant txs for blocks they are trying to attach). When a block is reorged out of the main chain, and a later reorg adds it back in, the relevant txs from this block are not recorded in the wallet any longer.