I started a fresh installation of 4.2.1 and after the system check I got a 500 error.
Files were found in your Matomo, but we didn’t expect them.
–> Please delete these files to prevent errors. <–
File to delete: php-fpm.core
I deleted the file, backed in the browser, reloaded the page, and got the same message to delete the file.
Deleted the file, clicked Next to go to database setup, blank screen.
I think there is something worng wih Matomo verion 4.2.1.