Error with WinClient

Hello

from one to another day I received an error message from Windows Client. See below. I deleted this account and added it again even with clean sync option error came back again.
All other sync accounts are running normally.

26.04.2017 22:16:07,                             GC/80-Tage-Finalvorbereitung-06.xls, E:\DATEN\CLOUD SPEICHER\homer,Error transferring http://192.168.100.39:82/owncloud/remote.php/webdav/GC/80-Tage-Finalvorbereitung-06.xls - server replied: Service Unavailable
26.04.2017 22:16:07,                                            Fond Berechnung.xlsx, E:\DATEN\CLOUD SPEICHER\homer,Error transferring http://192.168.100.39:82/owncloud/remote.php/webdav/Fond Berechnung.xlsx - server replied: Internal Server Error

Please fill out the issue template below (which is shown when creating a new thread in this category and as already pointed out in some of your previous threads). Currently even the basic information are missing which are mandatory to help here.

Please help us by providing the following info. Before posting please make sure that you're running the latest available version for your oC release: https://owncloud.org/changelog/ + https://owncloud.org/changelog/desktop/

[b]Steps to reproduce[/b]
1.
2.
3.

[b]Expected behaviour[/b]
Tell us what should happen

[b]Actual behaviour[/b]
Tell us what happens instead

[b]Client configuration[/b]
Client version:
Client operating system:

[b]Server configuration[/b]
Operating system:
Web server:
Database:
PHP version:
ownCloud version (see ownCloud admin page):
Updated from an older ownCloud or fresh install:
Special configurations (external storage, external authentication, reverse proxy, server-side-encryption):

[b]ownCloud log (data/owncloud.log)[/b]

Please paste possible errors in the following code block, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808 for more info
[code]

[/code]

The error message indicates a problem on your server. Check the apache error log there first, maybe you see the problem immediately.