[bug]: LND fails to sweep expired HTLC

[bufo24]

Pre-Submission Checklist

• I have searched the existing issues and believe this is a new bug.
• I am not asking a question about how to use lnd, but reporting a bug (otherwise open a discussion).

LND Version

0.21.1-beta

LND Configuration

LND config are Voltage defaults with the needed settings for tapd.

Backend Version

btcd from Voltage, version unsure

Backend Configuration

Managed by Voltage, config unsure

OS/Distribution

Bug Details & Steps to Reproduce

1. I tried to send a payment to LND
2. I later found out that the channel was online on 1 side but offline on the other, so the payments got stuck at the last hop.
3. The channel never came online so I force closed it.
4. There were 9 pending HTLCs in the channel which moved onchain.
5. I assume the preimage never got released, so the HTLC belong to my channel partner.
6. The funds got sweeped by the peer.
7. My node tries to sweep the HTLCs as well: Failed to sweep input: [txid:output] (HtlcAcceptedSuccessSecondLevel), error: input no longer exists. It didn't got local funds but it only tries to sweep the HTLCs. This keep the channel in a pending close state

Expected Behavior

It should see that the HTLCs didn't belong to the node and just mark the channel as closed.

Debug Information

2026-07-21 12:02:15.006 [WRN] SWPR: Failing record=1: found orphan inputs: 982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:1 (HtlcAcceptedSuccessSecondLevel)
10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:1 (HtlcAcceptedSuccessSecondLevel)
10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:3 (HtlcAcceptedSuccessSecondLevel)
10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:2 (HtlcAcceptedSuccessSecondLevel)
10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:4 (HtlcAcceptedSuccessSecondLevel)
982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:0 (HtlcAcceptedSuccessSecondLevel)
ac1a090ab3bfcef24cae80079b332dacf08413b9f156c8a943e146522eb6e9a5:0 (HtlcAcceptedSuccessSecondLevel)
10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:0 (HtlcAcceptedSuccessSecondLevel)
982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:2 (HtlcAcceptedSuccessSecondLevel)
2026-07-21 12:02:15.007 [INF] SWPR: Tx=70a45f1e3b05a40bebfa50c317d6885cd0b277e40594c2235965a0f510d16893 failed with unexpected error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:1 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:1 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:3 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:2 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:4 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:0 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: ac1a090ab3bfcef24cae80079b332dacf08413b9f156c8a943e146522eb6e9a5:0 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 10f1ac4c546c15d953d295af7f0b08c6a5e2276d92cd2347790f92bbcda946aa:0 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists
2026-07-21 12:02:15.008 [ERR] SWPR: Failed to sweep input: 982a77ad0f5803cf081aad976c8e4cc6219b96692a8ace2c1eb176db771b777a:2 (HtlcAcceptedSuccessSecondLevel), error: input no longer exists

Channel close TX: https://mempool.ainah.nl/nl/tx/72d6f19f075751731ef208c985206f59f762c2a1e77f6947476b06cfe45f1c19

All pending HTLCs were 30k

Environment

No response

[ziggie1984]

Thank you for reporting should be fixed with:

should be addressed with #10869 and #10842

[ziggie1984]

One possible explanation for why all 9 HTLCs remained unresolved is the litd/tapd custom-channel HtlcModifier.

lnd invokes this modifier after the HTLC is locked into the commitments but before it is written to the invoice DB. If the modifier blocks or its stream returns an error, the HTLC remains commitment-locked but unrecorded. The error also fails the channel link. In taproot-assets, AuxInvoiceManager logs Error setting up invoice acceptor and exits without reconnecting the modifier stream.

This could compose with #10869: after the force close, the on-chain resolver retries an unrecorded HTLC with currentHeight=0, potentially starting the success path after expiry even though the peer has already taken the timeout path.

Could the reporter check for these messages around the original payments/force close?

TCHN: Error setting up invoice acceptor
INVC: error during invoice HTLC interception
HSWC: failing link
INVC: Not intercepting invoice ... no intercept client connected

Also useful would be the invoice HTLCs' accept_height values. If all 9 are zero, with accept_time near the force close/restart, that would strongly suggest they first entered the invoice registry through the on-chain lookup rather than normal final-hop processing.

[bufo24]

I'm using the lightning lib for JS and ran into this issue, suggesting the accept_height was 0 indeed: alexbosworth/lightning#211.

I don't have access to the logs anymore from back then.

[ziggie1984]

hmm so having 9 htlcs in that way stuck and moreover the accepted_height being zero for all of them is very unlikely so keep a closer look to the litd logs, there might be a bigger problem which created these unresolved HTLCs in the first place.