I run NextCloud on Centos 7 with nginx but I’m sure the procedure is quite the same.
back up php.ini and php-fpm.conf
php -m to list all installed modules
remove php and all corresponding modules listed in step 2
install php 7.3 and all modules you had before…
May need to edit the .ini .or .conf as the listen directive maybe pointing to the old php .sock
Thank you for the hint, but I had already found the contribution to the slash at the end. But that does not change the result. It is still being replaced by the local URL.
I took that error as a hint that it was time for me to upgrade from 16.04 to 18.04.
It did not work without flaws following the do-release-upgrade, but all in all I got everything working within an hour or so.
I’m not sure how you’re using php, but I had to reinstall apache2 to get php7.2-fpm to install cleanly. That was when I found out that the custom settings I added to my php 7.0 conf for Nexcloud (opcache) weren’t carried over to the 7.2 conf.