Direct payment by channel doesn't include MPP payload.

[AllanLindJensen]

The MPP payload was apparently taken out recently for direct payment, but LND developer team states, that it must always be included, also when paying directly - for security reasons. To reproduce: Open a channel to an LND node. Have it iussuse an invoice. Pay it. The payment will fail.

[t-bast]

You're confusing two distinct things here. What's needed for security is the payment_secret and this should be supported by the latest version of eclair-mobile. But maybe your lnd node is requiring multi-part payments, is that the issue? If that's the case don't worry, it will be re-enabled in the next eclair-mobile release.

[AllanLindJensen]

The message in LND's log is: "[WRN] INVC: Payment to pay_hash=... doesn't include MPP payload, rejecting". The important part of the issue is that direct payment is refused by lnd. Naively, I think that the warning in the log means, that the payment fails to include the MPP payload.

[t-bast]

I think it's premature from lnd to make the MPP payload mandatory without discussing it with other implementations or giving them proper notice. Eclair-mobile had to disable MPP because the algorithm had issues on mobile, but it will be re-enabled in the next eclair-mobile release.

[AllanLindJensen]

Thank you for your reply. It explains why direct payment used to work, but failed after an update. I believe that the correct procedure is to close the issue, when I have seen that payments work after the next update; do you agree? When will it be rolled out?

Yours sincerely Allan

On Mon, 4 Jan 2021 at 09:46, Bastien Teinturier notifications@github.com wrote:

I think it's premature from lnd to make the MPP payload mandatory without discussing it with other implementations or giving them proper notice. Eclair-mobile had to disable MPP because the algorithm had issues on mobile, but it will be re-enabled in the next eclair-mobile release.

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-- Yours sincerely Allan Lind Jensen

[t-bast]

the correct procedure is to close the issue, when I have seen that payments work after the next update

Yes that sounds good, let's wait for the update to verify that it correctly fixes the issue before closing.

When will it be rolled out?

I'm not sure when exactly, I think @dpad85 had something close to being ready, but I don't know when we expect to release it.

[dpad85]

The new version enabling MPP back has been released and should be available shortly here and on Google Play.

[AllanLindJensen]

Solved in version 0.4.13