Description

This is not a bug, but should be mentioned in docs/workers.md:
If homeserver A sends an image to homeserver B, homerserver B is asking for the image on the federation port 8448 to get the media on URL /_matrix/media/. If (on homeserver A) worker_app: synapse.app.media_repository is enabled and client and federation are split to different vhosts (443 and 8448) the regex /_matrix/media/for the media worker must point to the internal media worker port in nginx vhost for federation port 8448 too. Otherwise homeserver B gets a 404 (not found) on the federation port 8448 of homeserver A. The mean thing is that on homeserver B, the user/client gets the message "Error decrypting image" and not something like "not found".

So it might be a good idea to mention under "synapse.app.media_repository" in docs/workers.md that the regex location /_matrix/media/ for the media worker must be available on client and federation port.

Version information

• Version: synapse 1.22.0

• Install method:
  debian package from https://packages.matrix.org/debian/