I issued a withdraw command with low fee, and the transaction was broadcasted, but miners didn't include it in blocks. But I can't withdraw again with a higher fee, it gives me error 301 - the coins have been marked as "spent". Listfunds shows empty wallet. The question is how to salvage the coins.
Should I clear bitcoind's mempool, will it help?
According to their Github(c-lightning) this error "301: There are not enough funds in the internal wallet (including fees) to create the transaction."
So it means you don't have enough funds when you are trying to withdraw. Read this from here
https://lightning.readthedocs.io/lightning-fundchannel.7.htmlWhat exactly command do you use can share it here
Then try this command in your lightning cli
lightning-cli listfunds
post the result here