can not log in to owncloud after upgrade 1.19 to 2.1.14

just updated 1.19 and 7.04 owncloud (using this guide Upgrade to OMV 2.x)
and now i can't log in to owncloud in browser, but ios client works ok
url opens ok, i'm entering name and password, page reloaded and asks me to enter name-password
tried to remove user, created new, problem remains

root@omvnas:/var/www/owncloud# sudo -u www-data php occ -vvv user:report
+------------------+---+
| User Report | |
+------------------+---+
| Database | 1 |
| | |
| total users | 1 |
| | |
| user directories | 7 |
+------------------+---+

but i have 3 users (including "admin")

root@omvnas:~# dpkg -l | grep openmediavault
ii openmediavault 2.1.14 all Open network attached storage solution
ii openmediavault-keyring 0.4 all GnuPG archive keys of the OpenMediaVault archive
ii openmediavault-nginx 2.0-2 all Nginx plugin for OpenMediaVault.
ii openmediavault-omvextrasorg 2.2 all OMV-Extras.org Package Repositories for OpenMediaVault
ii openmediavault-owncloud 2.0.3 all OpenMediaVault ownCloud plugin
ii openmediavault-plexmediaserver 1.0.12 all OpenMediaVault Plex Media Server plugin
ii openmediavault-remoteshare 1.1 all remote share plugin for OpenMediaVault.
ii openmediavault-transmissionbt 1.4 all OpenMediaVault Transmission (BitTorrent client) plugin.
ii openmediavault-virtualbox 1.3 all VirtualBox plugin for OpenMediaVault.

i disabled all apps, no changes,the same login loop

root@omvnas:/var/www/owncloud# sudo -u www-data php occ app:list
Enabled:
- files: 1.1.10
Disabled:
- activity
- encryption
- external
- files_external
- files_locking
- files_pdfviewer
- files_sharing
- files_texteditor
- files_trashbin
- files_versions
- files_videoviewer
- firstrunwizard
- gallery
- provisioning_api
- templateeditor
- user_external
- user_ldap
- user_openmediavault
- user_webdavauth
root@omvnas:/var/www/owncloud# service nginx restart
Restarting nginx: nginx.

log file (/var/log/nginx/owncloud_access.log)
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:56 +0300] "-" 400 0 "-" "-"
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:56 +0300] "POST / HTTP/1.1" 200 1888 "https://xxxxxx.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:56 +0300] "GET /index.php/core/js/oc.js?v=ecd78a5adf583367029586d31e2a31cc HTTP/1.1" 200 1408 "https://xxxxxx.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:57 +0300] "GET /core/img/breadcrumb.svg HTTP/1.1" 200 455 "https://xxxxxx.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:57 +0300] "-" 400 0 "-" "-"
::ffff:xxx.74.xxx.99 - - [14/Sep/2015:11:41:57 +0300] "GET /cron.php HTTP/1.1" 200 31 "https://xxxxxx.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.120 Safari/537.36"

added two (existed before upgrade) users
# sudo -u www-data php occ user:add --group="users" user1
# sudo -u www-data php occ user:add --group="users" user1
root@omvnas:/var/www/owncloud# sudo -u www-data php occ user:report
+------------------+---+
| User Report | |
+------------------+---+
| Database | 3 |
| | |
| total users | 3 |
| | |
| user directories | 7 |
+------------------+---+

no effect, login loop (but ios client works)

i tried to uncomment string: session.save_path = "/var/lib/php5" in /etc/php5/cgi/php.ini
it writes something (-rw------- 1 www-data www-data 348 Сен 14 14:41 sess_rp4guulbn7kk3rj0gba2b2j384)
but no effect, same login loop

what does this mean? files app is broken?

root@omvnas:/var/www/owncloud# sudo -u www-data php occ app:check-code files
Analysing /var/www/owncloud/apps/files/lib/helper.php
6 errors
line 45: OC_Helper - static method call on private class
line 46: OC_L10N - is instanciated
line 69: OC_Helper - static method call on private class
line 72: OC_Helper - static method call on private class
line 74: OC_Helper - static method call on private class
line 77: OC_Helper - static method call on private class
Analysing /var/www/owncloud/apps/files/ajax/mimeicon.php
1 errors
line 27: OC_Helper - static method call on private class
Analysing /var/www/owncloud/apps/files/ajax/scan.php
2 errors
line 36: OC_User - static method call on private class
line 41: OC_User - static method call on private class
Analysing /var/www/owncloud/apps/files/ajax/newfile.php
2 errors
line 76: OC_Helper - static method call on private class
line 77: OC_Helper - static method call on private class
Analysing /var/www/owncloud/apps/files/ajax/move.php
2 errors
line 43: != - is discouraged
line 43: != - is discouraged
Analysing /var/www/owncloud/apps/files/ajax/download.php
2 errors
line 42: == - is discouraged
line 42: OC_Files - static method call on private class
Analysing /var/www/owncloud/apps/files/ajax/upload.php
4 errors
line 60: OC_User - static method call on private class
line 80: OC_Util - static method call on private class
line 81: OC_Util - static method call on private class
line 115: != - is discouraged
Analysing /var/www/owncloud/apps/files/admin.php
3 errors
line 31: == - is discouraged
line 36: OC_Util - static method call on private class
line 38: OC_Files - static method call on private class
Analysing /var/www/owncloud/apps/files/index.php
4 errors
line 53: OC_Util - static method call on private class
line 78: OC_User - static method call on private class
line 84: OC_Helper - static method call on private class
line 110: OC_App - static method call on private class
Analysing /var/www/owncloud/apps/files/appinfo/remote.php
1 errors
line 34: OC_Util - static method call on private class
Analysing /var/www/owncloud/apps/files/appinfo/register_command.php
1 errors
line 23: OC_User - static method call on private class
Analysing /var/www/owncloud/apps/files/appinfo/app.php
1 errors
line 41: OC_Helper - static method call on private class
Analysing /var/www/owncloud/apps/files/download.php
2 errors
line 42: OC_Helper - static method call on private class
line 49: OC_Util - static method call on private class
App is not compliant

finally, i removed owncloud, reinstalled from web gui, and got 6.0.4
but it works