Update to Grav v1.7.50.2 destroys Admin panel

I used the Big Ptcture Skeleton to install grav that comes with v1.7.38.
After installation everything worked, but all the plugins need an update.
When i tried to update the plugins, it says “Version 1.7.49 is needed”. So i first updated grav to the latest available version (v1.7.50.2).
But after doing this, i’m not able to call the backend anymore - any admin/ path throws an “Not Found” error.
I retried it several times - what am i doing wrong?
EDIT:
Not only admin - no path is found anymore.

Are you doing the update locally (ie. on xammp)? I saw the same thing, though when out on the web, it all worked for me. And to get back to working on xammp, I created a backup and downloaded to the PC.

@kilowahn, check if the index.php file exists in the root folder. @basicchip, had the same issue on XAMPP after updating GRAV.

I just re-created this and on a PC/xampp when I updated Grav it removed the index.php file. Copying the file back fixed it.

That was the solution.
But, to be true - it’s not really a solution, since an update of the system should not delete the index.php…
;)