Users from matrix.org see Unable to decrypt

[matrixbot]

This issue was originally created by @ealib at matrix-org/dendrite#2436.

Background information

• Dendrite version or git SHA: 08.3rc1
• Monolith or Polylith?: monolith
• SQLite3 or Postgres?: Postgres
• Running in Docker?: No
• go version: go1.18.1 windows/amd64
• Client used (if applicable): Element Desktop

Description

• What is the problem: users from matrix.org can't read a message from a dendrite user
• Who is affected: users registered at matrix.org
• How is this bug manifesting: Element writes Unable to decrypt: The sender's device has not sent us the keys for this message.
• When did this first appear: randomly

Steps to reproduce

Sent via DM

[matrixbot]

This comment was originally posted by @ealib at matrix-org/dendrite#2436 (comment).

I upgraded Dendrite to 0.8.3 and tested it again.

matrix.org users in a room:

• can't decode messages posted by a Dendrite user X if Dendrite user X posted them with Element Desktop (1.10.11)
• can decode* messages posted by a Dendrite user X if Dendrite user X posted them with FluffyChat (1.4.0)

Notes:

• All Dendrite user X's sessions are verified.
• Element's cache cleared.

[matrixbot]

This comment was originally posted by @kegsay at matrix-org/dendrite#2436 (comment).

I'm debugging issus with flakey device keys currently which could cause this behaviour.

[matrixbot]

This comment was originally posted by @jittygitty at matrix-org/dendrite#2436 (comment).

Forget about complications of matrix.org to dendrite user. I have same error with simpler setup of both participants in direct-message connected to the "same" dendrite server. see:
element-hq/element-web#19748

[matrixbot]

This comment was originally posted by @S7evinK at matrix-org/dendrite#2436 (comment).

With a recent change /members, is this still happening? Is it better/worse?

[matrixbot]

This comment was originally posted by @ealib at matrix-org/dendrite#2436 (comment).

With a recent change /members, is this still happening? Is it better/worse?

Not recently (Dendrite 0.10.8+ba2ffb7d), but it may be related to #2890 .