"download failed" when using client-side decryption

I am using CE server 6.3.4 behind apache2 on ubuntu 16.04 plus seadroid client 2.2.8 on Android 7.0

With encrypted libraries and using local (client-side) decryption I can not download any files. I get 2 pop-ups saying “download failed” and then “failed to download file…”. If I change the client decryption setting to use server-side decryption it works fine. I can not find anything obvious in any log files so I am not sure where to look next.

Problem is the same on multiple android devices.

A bit of googling pointed me toward (maybe) ssl issues. So for testing I set up a second server in a vbox running without apache/nginix (so running without ssl). Interestingly this works correctly regardless of the client-side decrypt setting. (Of course there will be more differences than just the http(s) settings).

Any ideas on where to look?


I moved my test server behind apache so both servers are using https now, and they both show the problem.

For libraries with no encryption, or server-side decryption everything works well.

If I activate client-side decryption I get endless “download failed” problems. On each android device I have defined an account on each server. When I switch between accounts I invariably can download nothing. If I do a clear-cache it sometimes fixes it for a while, sometimes I have to clear-cache multiple times. And it usually breaks again after a few minutes. If I try to download a lot of files in one go it usually processes 10 or 20 and then crashes with “download failed” for the rest. Then the only way to download another file is to clear the cache … which loses all of the successful files!

The behaviour is unpredictable. It feels like maybe a timing problem. The pattern is similar on 2 separate android clients, but not identical. One of the clients paired with one of the servers seems to work better than all the others, but it is still unreliable.

My only “fix” is to revert to server-side decryption which works fine, but seems to defeat the purpose rather.

Question: the clear-cache option is settings erases all of the downloaded files. Does it do any other cleanup?