[TYPO3-dev] Error 'The requested resource "/login" was not found'

[Stefan Franke]

Hello,

I've kind of destroyed my TYPO3 8.7.9 instance, but I don't remember how (I was playing around with Composer, though this is not a Composer-installation of TYPO3). Frontend is working fine, when trying to access the backend, I'm confronted with the folloing TYPO3 Exception:

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#1425389240: The requested resource "/login" was not found. (More information)

TYPO3\CMS\Backend\Routing\Exception\ResourceNotFoundException thrown in file
/var/www/typo3-sources/typo3_src-8.7.9/typo3/sysext/backend/Classes/Routing/Router.php in line 78.
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I've tried a fresh install from my Git-Repository, but the error remains.

Can anyone suggest where I should start looking? Many thanks!

Regards,
Stefan