The simpler media website CMS
I have installed ZP 1.5.1 in Ubuntu 18.10 using PHP 7.2, Apache 2.4.34 and MySQL 5.7. I made sure all prerequisites are fulfilled and every tiny bit of the config is correct.
I also created an admin user. After that I wanted to create a restricted user but that fails every time. The error message is "password may not be empty" - which doesn't make sense because I entered the password, also in the repeat password field, of course.
This behaviour can be reproduced, I tried it on another server running Ubuntu 18.04.