Notifications App not working

Problem:
After enabling the Notification application, I do not see the icon in the upper right corner.

Capture

Nextcloud version (eg, 12.0.6) :
Operating system and version (eg, CentOS Linux release 7.4.1708) :
Apache or nginx version (eg, nginx/1.12.2) :
PHP version (eg, 7.1.10)

The output of your Nextcloud log in Admin > Logging:

Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:57:59+0300
Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:57:56+0300
Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:57:06+0300
Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:57:03+0300
Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:55:54+0300
Error no app in context Symfony\Component\Routing\Exception\RouteNotFoundException: Unable to generate a URL for the named route “theming.Theming.getLogo” as such route does not exist. 2018-03-27T12:53:07+0300