Fatal Error after trying to update from 2.2.3 to Kirby 3

Hey guys,
I’m trying to update my Kirby site from version 2.2.3 to the latest version. I followed the upgrade/migration guidelines but after finishing all tasks, I only get the following PHP fatal error:

Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 12288 bytes) in /xxx/kirby/config/roots.php on line 83

The error appears on both the frontend and the backend - I can’t load any page at all. When I reload the page, the line and the amount of bytes will change. I’m running Kirby using MAMP with PHP 7.2.10. Can you give me any hint on what might be the issue here? I haven’t found any similar problems in the forum. Cheers!

Something is very wrong here - 1073741824 bytes is over a gigabyte.

Can you run the Starterkit ok on Mamp?