Hi All,
So here I am with the exact same issue.
Upgraded php7.0 to php7.3
All working fine, but apache still using 7.0
So I ran a2dismod7.0 and a2enmod7.3
Bam. No more Nextcloud ==> Internal Server error
Although phpmyadmin still works, and does register now that it is indeed using php7.3…
HALP ! 