INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS when paying to Phoenix

[adambor]

I am investigating an issue with one of our customers receiving LN payment to his Phoenix wallet. We are running LND v0.17.3-beta and some payments to him recently failed with INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS error message:

"failure": {
    "code": "INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS",
    "channel_update": null,
    "htlc_msat": "0",
    "onion_sha_256": "",
    "cltv_expiry": 0,
    "flags": 0,
    "failure_source_index": 3,
    "height": 832277
}

This never happened before (with ~250 successful payments to his wallet over past 3 months). So I am wondering if it's a problem on our side or Phoenix's side. What's also interesting is that it seems to only happen for some payments today, out of 15 payments, 5 payments failed with such a message, others were successful.

[dpad85]

This error is returned by Phoenix when someone is trying to pay an invoice that has already been paid, or if the incoming amount is below the expected amount.