Hi,
I’m not familiar with Matrix Synapse, as I don’t have it installed on my FreedomBox, so I don’t know if I’m the most qualified to answer this, but I’ll try to help.
Probably, by looking at the packages from the error, I see that matrix-synapse is coming from “forky” and requires a version of python3-rpds-py that is not available on “trixie”. It is also not available on “trixie-backports” yet.
Personally, I would wait for the developers to fix this, which might take some time. However, if Matrix Synapse is vital for your use case and you don’t mind trying things you could try something like the following:
Note: Mixing suites could break things.
So, if I had to find a solution, I suppose I’d check if other packages depend on python3-rpds-py and if not, I would pin the “forky” version of the package.
You could test if installing the python dependencies from “forky” would break things by doing from the command line:
apt-get -t forky -s install matrix-synapse
Source: [SOLVED] How to upgrade matrix-synapse from stable to buster-backports? - #2 by rgb
This will do a dry run and won’t install anything but you can see if the command succeeds or fails for some reason.
If it succeeds, you can consider running it for real by removing the -s option.
This, of course, would be a temporary fix and you should probably pin it with a apt “preferences” file. That said, since the package might be added to backports in the future, you could run the command manually when needed until it becomes available in trixe-backports.
On a different note, since you are asking for support, it would be very helpful for those trying to help you that you select the “Support” category. This will provide you with a template to present your issue, where it will show you information you can provide that might aid others to test and troubleshoot your issue with the same or similar environment to yours.
I hope this helps.