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element-hq / element-web

A glossy Matrix collaboration client for the web.
https://element.io
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"Unable to decrypt: OLM" only between two specific sessions, only in one specific room #18300

Open delroth opened 3 years ago

delroth commented 3 years ago

Description

On one specific room (with e2ee enabled), on only one of their sessions, one other user cannot see messages I send from one of my sessions. From any other pair of sessions things work fine, we've also not managed to reproduce the issue on any other room. This manifests as an "Unable to decrypt: OLM" error.

In case it matters, the pair of sessions in question show up as properly "verified" in the Element UI, and neither of us are getting decryption issues from any other users in that room.

Steps to reproduce

The bug reproduces consistently in the conditions described in the description above, but we've yet to manage to reproduce it in other situations (other sessions, other rooms). I'd appreciate feedback as to how we could provide more useful debugging information without leaking too much information on the particular room (e.g. identities of other participants -- I think me and the person getting the error would be fine with our personal information being attached, but I can't speak for anyone else in the room).

Version information

The sending session on my side is Element web v1.7.31, olm version v3.2.3. The receiving session on the other user's side is Element Android v1.1.14, olm version v3.2.4.

pwinckles commented 3 years ago

I experienced this issue this morning in a room that had been working fine for months.

Sending session:

Version: 1.3.3 [40103030] (F-651e3478) Matrix SDK: 1.3.3 (651e3478) OLM: 3.2.4

Receiving session:

Version: 1.3.3 [40103031] (G-b3874) Matrix SDK: 1.3.3 (651e3478) OLM: 3.2.4

Room version: 5

Other rooms between these sessions still work fine. And clearing the cache had no effect.

pwinckles commented 3 years ago

I was able to resolve the problem (for new messages) by reinstalling the sending client

Edit: Note, I only tried clearing the cache on the receiving device earlier. So, it is possible that clearing it on the sending device would have resolved the problem without needing the reinstall.