MAIL 0.5.2 APP account update problem

Please help us by providing the following info. Before posting please also check the pinned "Known issues" threads and make sure that you're running the latest available version for your oC release: https://owncloud.org/changelog/

Steps to reproduce
1. activate mail app and register an mail external account --> mail app will work ok
2. change the external password mail account
3. entry in mail app

Expected behaviour
I expect to have the possibility to update the account mail password

Actual behaviour
the webpage remain in upload with account upload error message and I cannot do nothing

Server configuration
Operating system: debian 8
Web server: apache2
Database: MySQL 14.14
PHP version: 5.6.24
ownCloud version (see ownCloud admin page): 9.1.0
Updated from an older ownCloud or fresh install: update
ownCloud log (data/owncloud.log, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808):

Special configuration (external storage, external authentication, reverse proxy, server-side-encryption):

Integrity status for oC9+

[code]
Login as admin user into your ownCloud and access
http://example.com/index.php/settings/integrity/failed
paste the results here.
No errors have been found.

Hi,

this is a known and not yet resolved bug in that app: