kolab_files: Authenticate error (Status: 404)

[Henning]

Hi!

yesterday I started the update procedure on my kolab server to 3.1. 
After resolving some package dependency loops (self-caused I guess), 
kolab seems to work again.

However roundcube throws errors, more precisely the kolab_files plugin:

PHP Error in 
/usr/share/roundcubemail/plugins/kolab_files/lib/kolab_files_engine.php 
(566): Authenticate error (Status: 404)

I see this message in the mail-content frame and on the files-tab in 
roundcube.

I use a https-conection with self-signed certificate and had to disable 
certificate-verification in the Request2 php-module. Could this also 
have something to do with the certificate?

Any help is appreciated.

regards,
Henning