Not able to see more than login page after upgrade to 14.0.0

Nextcloud version (eg, 12.0.2): 14.0.0
Operating system and version (eg, Ubuntu 17.04): Ubuntu 18.4.1
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.29
PHP version (eg, 7.1): 7.2

The issue you are facing:

1.) Go the login page
2.) I enter the login information
3.) The information is processed
4.) I get the login page

When entering a wrong password I get the message about the wrong password, but with the right one I stay an the same page.

Is this the first time you’ve seen this error? (Y/N): Y

The error is since the upgrade via web from 13.0.6 to 14.0.0

The output of your Nextcloud log in Admin > Logging:

No entries after a restart and a failed login

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

Not changed by me since 13.0.6

The output of your Apache/nginx/system log in /var/log/____:
Apache access log:

2001:16b8:201e:9501:f149:b9a6:900a:c4cc - - [11/Sep/2018:22:13:28 +0200] "GET /login?redirect_url=/apps/music/ HTTP/1.1" 200 8668 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36"
2001:16b8:201e:9501:f149:b9a6:900a:c4cc - - [11/Sep/2018:22:13:29 +0200] "GET /core/img/favicon.ico HTTP/1.1" 200 3839 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36"
2001:16b8:201e:9501:f149:b9a6:900a:c4cc - - [11/Sep/2018:22:13:31 +0200] "POST /login?redirect_url=/apps/music/ HTTP/1.1" 303 1465 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36"
2001:16b8:201e:9501:f149:b9a6:900a:c4cc - - [11/Sep/2018:22:13:32 +0200] "GET /apps/music/ HTTP/1.1" 303 1700 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36"
2001:16b8:201e:9501:f149:b9a6:900a:c4cc - - [11/Sep/2018:22:13:32 +0200] "GET /login?redirect_url=/apps/music/ HTTP/1.1" 200 5249 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.34

Apache error log:

[Tue Sep 11 22:15:59.077378 2018] [autoindex:error] [pid 15062] [client 2001:16b8:201e:9501:f149:b9a6:900a:c4cc:60282] AH01276: Cannot serve directory /var/www/cloud/: No matching DirectoryIndex (none) found, and server-generated directory index forbidden by Options directive

I don’t think this line has something to do with the problem.

Perhaps that is the problem:

{“reqId”:“OReElQpmiwnesvI5CnIh”,“level”:0,“time”:“September 11, 2018 23:24:14”,“remoteAddr”:“2001:16b8:201e:9501:f149:b9a6:900a:c4cc”,“user”:"–",“app”:“core”,“method”:“GET”,“url”:"/apps/files/",“message”:{“Exception”:“OC\AppFramework\Middleware\Security\Exceptions\NotLoggedInException”,“Message”:“Current user is not logged in”,“Code”:401,“Trace”:[{“file”:"/var/www/cloud/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php",“line”:95,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\Security\SecurityMiddleware”,“type”:"->",“args”:[{“class”:“OCA\Files\Controller\ViewController”},“index”]},{“file”:"/var/www/cloud/lib/private/AppFramework/Http/Dispatcher.php",“line”:98,“function”:“beforeController”,“class”:“OC\AppFramework\Middleware\MiddlewareDispatcher”,“type”:"->",“args”:[{“class”:“OCA\Files\Controller\ViewController”},“index”]},{“file”:"/var/www/cloud/lib/private/AppFramework/App.php",“line”:118,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Files\Controller\ViewController”},“index”]},{“file”:"/var/www/cloud/lib/private/AppFramework/Routing/RouteActionHandler.php",“line”:47,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::",“args”:[“ViewController”,“index”,{“class”:“OC\AppFramework\DependencyInjection\DIContainer”},{"_route":“files.view.index”}]},{“function”:"__invoke",“class”:“OC\AppFramework\Routing\RouteActionHandler”,“type”:"->",“args”:[{"_route":“files.view.index”}]},{“file”:"/var/www/cloud/lib/private/Route/Router.php",“line”:297,“function”:“call_user_func”,“args”:[{“class”:“OC\AppFramework\Routing\RouteActionHandler”},{"_route":“files.view.index”}]},{“file”:"/var/www/cloud/lib/base.php",“line”:989,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->",“args”:["/apps/files/"]},{“file”:"/var/www/cloud/index.php",“line”:42,“function”:“handleRequest”,“class”:“OC”,“type”:"::",“args”:[]}],“File”:"/var/www/cloud/lib/private/AppFramework/Middleware/Security/SecurityMiddleware.php",“Line”:143,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36”,“version”:“14.0.0.19”}
{“reqId”:“YdCyDttqRpull9gmnzXN”,“level”:0,“time”:“September 11, 2018 23:24:14”,“remoteAddr”:“2001:16b8:201e:9501:f149:b9a6:900a:c4cc”,“user”:"–",“app”:“no app in context”,“method”:“GET”,“url”:"/login?redirect_url=/apps/files/",“message”:“No cache entry found for /appdata_oca832fb7600/theming/images/background (storage: local::/srv/cloud-data/, internalPath: appdata_oca832fb7600/theming/images/background)”,“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36”,“version”:“14.0.0.19”}