[sync] ActiveSync stopped working

[Alex]

Dear all,

I am on horde webmail 5.2.19. All applications are up to date. I have a
problem with ActiveSync: Since a few days ActiveSync stopped syncing new
emails. On all my phones (android and ios) the system does not sync new
emails after a specific mail from 5 days ago.


I have the following error messages in horde.log:
2017-04-16T12:50:28+02:00 INFO: HORDE [imp] FAILED LOGIN for xxx  to
{imap://localhost/} [pid 1173 on line 157 of
"/usr/local/share/horde/imp/lib/Auth.php"]
2017-04-16T12:50:29+02:00 NOTICE: HORDE Login failed from ActiveSync client
for user xxx. [pid 1173 on line 578 of
"/usr/share/php/Horde/ActiveSync.php"]
2017-04-16T12:50:30+02:00 ERR: HORDE Sending HTTP 401 Unauthorized header
response. [pid 1173 on line 158 of
"/usr/share/php/Horde/Rpc/ActiveSync.php"]

Username and password are of course correct and the old emails show up on
the phone. I can still use Username and Password to log on to the
Webinterface of horde.

Does anybody have an idea how to debug this?

Thank you for your support
Alexander