For what it’s worth for future reference, my situation:
Intention: Upgrade from PHP 7.0 to PHP 7.2 with no other changes (no owncloud upgrades at the same time, to help ensure that any faults are isolated only to the PHP update)
Issue: After finally finding all the required packages (in plain site: https://doc.owncloud.org/server/10.3/admin_manual/installation/manual_installation.html#install-the-required-packages)
I managed to get my login page up, but logging in achieve this error that it took too long.
Solution: My server logs gave me the following gripe: “message”:"Unknown: POST Content-Length of 127 bytes exceeds the limit of 2 bytes at Unknown#0
Which led me to update my php.ini file with huge limits on max_execution_time, max_input_time, memory_limit, post_max_size and one other.
This didn’t work.
I then create a quick php info file
and find there’s an owncloud config file that I didn’t know about (didn’t remember): /etc/php.d/owncloud.ini
I update the two values in here to a suitable format (I had GB instead of just G after the numbers, must have been OK in old PHP version) and that fixes my issue. Restart httpd service each change of course.