Channel funding error: peer aborts dual funding flow during TxAddOutput (mainnet, v0.7.3)

[Harrison-F]

Description

New phoenixd instance (v0.7.3, macOS arm64, mainnet) consistently fails to open a channel. ACINQ's node accepts the dual funding request but aborts during transaction construction.

Steps to reproduce

1. Fresh phoenixd install, first-time channel creation
2. Accumulate fee credit via small payments (4,246 sats total)
3. Send a payment large enough to trigger channel creation (19,800 sats)
4. Channel negotiation starts, ACINQ sends AcceptDualFundedChannel, but then sends TxAbort("channel funding error") after our TxAddOutput

Behavior

The flow proceeds normally through:

• Payment received via on-the-fly funding
• Fee/liquidity assessment passes
• OpenDualFundedChannel sent (channelType=simple_taproot_channel, requestedAmount=2,019,800 sat)
• AcceptDualFundedChannel received (fundingAmount=2,034,800 sat, FeeCreditUsedTlv=4,246,000 msat)
• TxAddOutput sent

Then ACINQ's node responds with:

TxAbort(data="channel funding error")

Channel state: WaitForFundingCreated -> Aborted

Details

• This happens every time — tested 4 consecutive attempts
• Occurred on both v0.7.2 and v0.7.3
• Fee credit is preserved between attempts (still 4,246 sats)
• Payments are refunded to the sender
• The ACINQ node connects successfully, Init handshake completes, fee credit is acknowledged

Relevant log excerpt (v0.7.3)

2026-03-21T02:11:24 Info: requesting on-the-fly channel feerate=632 sat/kw fee=22225 sat paymentType=FromFutureHtlc
2026-03-21T02:11:24 Info: received AcceptDualFundedChannel fundingAmount=2034800 sat FeeCreditUsedTlv=4246000 msat
2026-03-21T02:11:24 Info: WaitForAcceptChannel -> WaitForFundingCreated
2026-03-21T02:11:24 Info: sending TxAddOutput amount=2034800 sat
2026-03-21T02:11:25 Info: received TxAbort data="channel funding error"
2026-03-21T02:11:25 Warn: our peer aborted the dual funding flow: ascii='channel funding error'
2026-03-21T02:11:25 Info: WaitForFundingCreated -> Aborted

Environment

• phoenixd v0.7.3-ef2caea (also tested on v0.7.2-1b6c08d)
• macOS 15.7.4, arm64 (Apple Silicon)
• Chain: mainnet
• No prior channels (fresh install)
• ACINQ peer: 03864ef025fde8fb587d989186ce6a4a186895ee44a926bfc370e2c366597a3f8f

Questions

1. Is this a known transient issue with ACINQ's funding infrastructure?
2. Is there anything on the client side that could cause the peer to abort at the TxAddOutput stage?
3. Is the generic "channel funding error" message expected, or should there be more detail?

Similar to #103 (testnet), but this is on mainnet with the latest release.

[t-bast]

Can you share your node_id or payment_hash? We can't investigate without details about the specific funding attempt.