thank you, this resolved the error message.
Although, now I cannot log in. Tried (username, password): dietpi, dietpi; root, dietpi; dietpi, <globalpassword>; root, <globalpassword>; freshrss, <globalpassword>, etc.
In FreshRSS config, freshrss, dietpi and <globalpassword> is correctly configured for mariadb access, as far as I can tell.
Following https://github.com/FreshRSS/FreshRSS/is ... -185222031
I set 'auth_type' => 'none', but after reboot, FreshRSS returns a HTTP 500 error on http://192.168.8.125/freshrss/i/
Manually loading http://192.168.8.125/freshrss/i/?c=user&a=profile
returns a valid website, where I can change the 'dietpi' password, but upon clicking save, it returns to a HTTP 500 error.
I think I set 'auth_type' => 'form' again, reboot, reload http://192.168.8.125/freshrss/i/?c=user&a=profile
, which allowed me to reset the password again, after which it saved correctly, but now:
When I log in with incorrect details, logon screen shows 'invalid password' (correct behaviour; previously returned OP error message)
When I log in with correct details, the logon screen proceeds to a HTTP 500 error.
I'll try playing around with this later again. For now, I uninstalled it, cleared it's directory in /opt/ and deleted the database (so I can start with a clean slate)
Since you resolved my initial issue, I'm marking your answer as the solution, and the rest of the issues here are with FreshRSS and it's conflicts with PiHole (probably) or misconfigured MariaDB database, and not with DietPi itself. My money is on PiHole, since any url following dietpi, e.g. http://192.168.8.125/fakesite
, returns PiHole's webpage "did you mean to go to the (PiHole) admin panel?"