Payment failed: UNIMPLEMENTED HTTP status code 404

I could not pay an invoice on the app.

Description

UNIMPLEMENTED: HTTP status 404 invalid content-type: null
trailers:
Metadata(:status=404,server=nginx,content-length=0,referrer-policy=same-origin,x-xss-protection=1;mode=block;x-content-type-options=DENY,strict-transport-security=max-age=31536000)

Steps to Reproduce

1. Access BTCPayServer via IPV4.
2. Services > LND (gRPC server).
3. Scan the QR Code on ZapWallet.
4. Attempt to pay an invoice.

Environment

• Zap version: 0.4.0-beta, build: 3027
• Android version: Android 11 API 30
• Device: Mi A3
• LND Version: 0.11.0-beta
• BTCPayServer version: 1.0.7.1

[michaelWuensch]

Hey guys, now that 3 of you are affected, I can at least see a pattern. It seems to be definetly related to using Zap with BTCPAYServer. But unfortunately I still have no clue so far why this happens.

[michaelWuensch]

Hm, okay this means, the UNIMPLEMENTED error is caused by the SendPaymentV2 RPC call. “UNIMPLEMENTED” normally comes if the RPC call is not available/implemented on the lnd node you are running. The strange thing is that lnd 0.11.0-beta includes the SendPaymentV2. I tested it on regtest with 0.11.0 nodes and it worked. I do not have (or ever used) a BTCPay setup though.

The change for the payment flow was made in the last update (Zap Android 0.4.0-beta) where I replaced the deprecated functions.

Updating your LND node might help. If you don’t want to do that, I would suggest to downgrade to Zap Android v0.3.8-beta version from the github releases in the meantime. (https://github.com/LN-Zap/zap-android/releases) Once you have updated your lnd, you can give the newest version of Zap Android a try again.

So far I have only heard of this issue with LND v0.11.0. If anyone with a newer version has the same issue, please write a comment here.