eclair refuses cooperative channel closure, demands higher fee than peer is willing to pay

[viaj3ro]

my eclair node refuses to cooperate in two channel closures initiated by a LND peer.

2025-07-06 07:33:32,028 WARN f.a.e.c.fsm.Channel n:0206db3b9c7475b246d380987bb77cf55acb65e2b0913b6e7d97063efd6d3d3d95 c:6526d38a9c09de6c97838ee444d1d6e54e613aa23455bc393baa17b12d51685f - their highest closing fee is below our minimum fee: 319 sat < 1805 sat

relevant logs: https://pastebin.com/PusPYAnp

one hour later there was another attempt, which was also refused:

2025-07-06 08:30:08,972 WARN f.a.e.c.fsm.Channel n:0206db3b9c7475b246d380987bb77cf55acb65e2b0913b6e7d97063efd6d3d3d95 c:6526d38a9c09de6c97838ee444d1d6e54e613aa23455bc393baa17b12d51685f - their highest closing fee is below our minimum fee: 302 sat < 1805 sat

relevant logs: https://pastebin.com/nMhzkNVE

The channel is stuck in negotiation since more than 7 hours.

[viaj3ro]

After restarting my node, one of the two channels successfully closed: https://pastebin.com/WLbiFYjm

The other one was attempted to close again as well but no success: https://pastebin.com/TqUVh1nw

2025-07-06 18:56:57,736 WARN f.a.e.c.fsm.Channel n:0206db3b9c7475b246d380987bb77cf55acb65e2b0913b6e7d97063efd6d3d3d95 c:6526d38a9c09de6c97838ee444d1d6e54e613aa23455bc393baa17b12d51685f - their highest closing fee is below our minimum fee: 350 sat < 361 sat

restarted my node a few more times but no success.

manually disconnecting and reconnecting this peer didn't help either and neither did another manual close attempt via API.

Edit:

finally got it closed by setting eclair.on-chain-fees.min-feerate from 2 down to 1 but this shouldn't be necessary.

[t-bast]

Closing channels is notoriously problematic, because if nodes disagree on feerate, they will not reach an agreement. As you're highlighting, the issue is that you had set eclair.on-chain-fees.min-feerate to 2 sat/bytes, so it makes sense to reject remote feerates which are below your configuration.

However, the real fix is lightning/bolts#1205 which finally lets each node decide what feerate they want to pay for their version of the closing transaction. This has been implemented in eclair and lnd, I'm just not sure why lnd hasn't activated it by default yet. I believe they will turn it on by default in their next release, which will fix this.

[viaj3ro]

But why didn't it work even though the respective fee ranges were clearly overlapping:

2025-07-06 18:48:33,173 INFO f.a.e.c.fsm.Channel n:0206db3b9c7475b246d380987bb77cf55acb65e2b0913b6e7d97063efd6d3d3d95 c:1082721a85e85e604e14512f9a30de163e8d8edbf3d524388bfb0734493c3b20 - proposing closing fee=361 sat in their fee range (min=183 sat max=2334 sat)

That's the part that doesn't make sense to me. Looks like the nodes just stopped negotiating.

[t-bast]

AFAIK lnd doesn't "negotiate" at all here, they just only accept their initially proposed value...because here eclair behaves correctly (proposes a value in the range lnd gave us), so if the mutual close doesn't complete it means lnd incorrectly ignores that value that they should accept.

[viaj3ro]

worth posting an issue in their repo? or is this obsolete very soon anyway due to lightning/bolts#1205?

[t-bast]

I'm almost certain they will turn on option_simple_close by default in their next release, which will make the previous closing protocol obsolete, so I don't think this is worth an issue to be honest.

[t-bast]

I'm closing this issue since there's no action to take on the eclair side, feel free to re-open if we should make a code change for some reason.