Hello @OstharzRC and @wwe . I am also experiencing this frustrating issue. It has been very hard to diagnose the cause. The issue sometimes “fixes itself”, but just yesterday this dreaded white screen with no scroll bars returned after a reboot of the server.
Flushing the browser cache makes no difference and this occurs on mobile, desktop, chrome browser, and gecko based browsers.
I found similar issues here, here, and here but these are for different NC versions and I’m hesitant to try anything like an upgrade or disabling essential apps like dashboard for fear of wrecking things further.
The only error in administration/logging is this WebAuthn Error but I can’t see how that could be related?
Summary
index Exception: OC\Core\Controller\WebAuthnController::finishAuthentication(): Argument #1 ($data) must be of type string, null given, called in /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php on line 230 in file '/var/www/nextcloud/core/Controller/WebAuthnController.php' line 93
/var/www/nextcloud/lib/private/AppFramework/App.php - line 183:
OC\AppFramework\Http\Dispatcher->dispatch()
/var/www/nextcloud/lib/private/Route/Router.php - line 315:
OC\AppFramework\App::main()
/var/www/nextcloud/lib/base.php - line 1056:
OC\Route\Router->match()
/var/www/nextcloud/index.php - line 36:
OC::handleRequest()
Caused by TypeError: OC\Core\Controller\WebAuthnController::finishAuthentication(): Argument #1 ($data) must be of type string, null given, called in /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php on line 230
/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php - line 230:
OC\Core\Controller\WebAuthnController->finishAuthentication()
/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php - line 137:
OC\AppFramework\Http\Dispatcher->executeController()
/var/www/nextcloud/lib/private/AppFramework/App.php - line 183:
OC\AppFramework\Http\Dispatcher-
Could there be some kind of missing CSS files for the GUI? If so how could we troubleshoot that?
Finally, I’ve observed that the default theme directory /var/www/nextcloud/themes/ is empty except for an example folder and README file. The theme parameter in config.php is also an empty string like so 'theme' => ''.
Is this normal? Could the themes have gotten deleted on their own somehow and this is the cause? How can we recover the missing themes if so? Any guidance at all is much appreciated.