can't access channel.db for removechannel due to "locked" or "lnd running" error

[fredmarti]

i'm trying to use removechannel to clear channel openings that remain pending due to low fees. It fails on nodes on both MyNode and Umbrel, with a "running" lnd or "locked" channel.db error message. I've changed permissions on the channel.db, and copied and pasted new channel.db files with no result. I've shutdown ltn from the GUI on MyNode and via lncli on the Umbrel. It's either ineffective on the Umbrel or the Umbrel spontaneously restarts.

[guggero]

You can use lncli abandonchannel (check the output of --help for instructions on how to use the command) instead of chantools removechannel. But for that, you need to make sure the funding transactions can never confirm! You do that by making sure at least one input of the original funding transaction has been spent (and confirmed) by now. Only then is it safe to remove the channel (with either method!).

[fredmarti]

Thank you for your expertise. Before I started this I studied everything I could find, including your posts on similar issues, which were the most helpful. I came to the conclusion that incli abandonchannel was less safe than chantools removechannel. Also, I've not understood how to make sure one input of the original funding transaction has been spent. There was only one input, and since the channel never opened, it's still unconfirmed. Do I need to double-spend it first?

[guggero]

Yes, if you want to make 100% sure the channel can never confirm (you never know if it's still in a mempool somewhere), you should double spend the input used in the channel funding transaction. You can use chantools doublespendinputs.