…fy any which may fix the issue.
To test run the following command in the piwik directory:
rm js/.htaccess plugins/.htaccess core/.htaccess libs/.htaccess vendor/.htaccess misc/user/.htaccess
(this deletes all current htaccess files)
Then visit the System check page
(this re-creates the .htaccess files)
Then browse Piwik -> is it working fine?
If not, check your error log and please paste error as a comment in the ticket.