Unable to debug Panel Login Issue after login

Today, I fetched the content files via rsync from my clients remote server to work locally on new things. But now I get this error accessing the panel (directly after submitting the login form):

Argument 1 passed to Kirby\Toolkit\Str::before() must be of the type string, null given, called in /Users/macx/Projects/amazing-outcomes/ao-website/dist/kirby/src/Cms/Language.php on line 460

I don’t know how to identify the problem. Strange. Language.php only have 110 lines of code, not 460. How can I debug this issue?

Are you using the same version of PHP locally? there should be more information with this error, like the actual code that caused it. On the left of the error page, that columns shows the process. somewhere in there will be the snippet or template that did something wrong here. Im guess its a bad entry in a field somewhere.

I just noticed this is a panel error not a whoops on the front end. I guess you could try updating kirby if its not already at the current version, and making sure you are using the correct version of PHP locally.

Kirby is up-to-date (was my first try), it’s the same PHP-Version (7.3) and yes, it’s a panel-error without the „Tree of problems“. :wink:

The file has more than 700 lines and yes, there is a line 460…

Is the locale set in the language files?

Good hint, @pixelijn. The german language file has a wrong key for whatever reason:

'locale' => [
  6 => 'de_DE.utf8'