Try upgrading the version of php from php-7.2 to PHP-7.3 in your apache2
Was facing similar issue because when I updated stuffs manually, I inadvertently updated my php from 7.2 to 7 3 and hence all my installed modules were migrated from 7.2 to 7.3. So my OS was ready for 7.3 but my apache2 was still configured to use 7.2. Hence my redis caching was not working and I got an “Internal Server Error”
Refer my post here for the command to execute to change apache2 to use 7.3 and disable 7.2