Transaction errors: ExpiredUTxO

Problem: ExpiredUTxO

$ cardano-cli shelley transaction submit \
> --tx-file tx001.signed \
> --testnet-magic 42

ApplyTxError [LedgerFailure (UtxowFailure (UtxoFailure 
(ExpiredUTxO {pfUTXOttl = SlotNo {unSlotNo = 123456}, 
pfUTXOcurrentSlot = SlotNo {unSlotNo = 123457}})))]

Diagnostic:

TTL has already passed. 

Solution:

Look at pfUTXOttl and pfUTXOcurrentSlot. Current Slot is ahead of UTXOttl. 

Build a new transaction with a TTL (Time to Live) higher that Current Slot. As a rule of thumb, give yourself a 300-500 slots to builld, sign and submit the transaction.