Stuck wait-close channels: “fee rate delta is zero"

[smashtrick]

Background

• LND Version: v0.18.3-beta
• Running on: Raspberry Pi 4
• Backend: Bitcoin Core v24.0
• RTL Version: v0.15.2
• Network: Mainnet

Problem

I have several wait-close channel that has been stuck for 2+ months. After trying lncli wallet bumpfee, the logs show:
[ERR] SWPR: Failed to sweep BudgetInputSet(budget=0.00000330 BTC, deadline=875727, inputs=[934ee7e2c5b61d5a7dc76c23a3216427176274782c11f521fc74c0f2b61b133b:0]): init fee function: fee rate delta is zero

The pendingchannels output shows:
"closing_txid": "b3ac2eaec8789895ec8e35f3410e4fed6396bba9ccf1f7a87ad71974b6c3cb65", "limbo_balance": 223797

I tried the following:

• Bumping fees multiple times. I was able to apparently successfully bumb fee "Successfully registered rbf-tx with sweeper” but it still never showed up in mempool.
• Manually restarting LND.
• Checking lncli listchaintxns but the transaction doesn’t show up.
• No closing_tx_hex available in the logs.
• Force close and lnd response is: channel is already in the process of being force closed

What I Need

• How can I manually broadcast or force this transaction?
• Should I consider using SCB recovery, or is there another way to recover the limbo balance?

[ziggie1984]

Can you verify that the channel you are trying to close exists onchain?

Moreover when trying to bump fees via the sweeper please read the sweeper doc thoroughly:

https://github.com/lightningnetwork/lnd/blob/master/sweep/README.md