When moving my test environment from Apple Intel (Zenphoto 1.6.4 on Ubuntu 23.04, PHP 8.1.12 under VirtualBox 7.0.14) to Apple Silicon (Zenphoto 1.6.4 on Ubuntu 24.04, PHP 8.1.34 under VirtualBox 7.2.12 - I didn't get warm with MAMP), I received the error message “A configuration error occurred, please return later” when I first launched Zenphoto. The database login credentials appeared to be correct in ../zp-data/zenphoto.cfg.php.
After a few unsuccessful attempts, I renamed that file — but didn't delete it — in the hope that it would be rewritten during installation. Note: I knew the login credentials. That was the solution, and the installation started. Afterward, I compared the contents of the old and new file:
old: conf['db_software'] = "MySQLi";
new: conf['db_software'] = "mysqli";
I'm not kidding!
Conclusion: If a configuration error has occurred and you know the database login credentials: try to rename the file ../zp-data/zenphoto.cfg.php and restart setup to enter the login credentials again. Setup will run as usual and the configuration file will be written with the correct login credentials.
I hope this helps someone who has the same problem as I did.

Have fun with zenphoto, cheers, imagepet

Glady you somehow solved it. You could just have deleted the config file, re-run setup and it should ask for credentials and recreate it.

old: conf['db_software'] = "MySQLi";
new: conf['db_software'] = "mysqli";

Actually the first mixed case writing is the one used. But Zenphoto 1.6.4 is of course already two years old and the current version is 1.6.8 ;-)

VirtualBox 7.2.12 - I didn't get warm with MAMP

MAMP has its issues, especially currently… I was not aware of Virtualbox, but the company behind it is a bit "difficult" acting at times but seems this is openly licensed. Maybe worth a try at some time.

acrylian, you're right: 1.6.4 is old but I got stuck on my way to 1.6.8... After successfully moved to the new machine now, I'll go on.

I saved the configuration file to compare it with the new one to find the difference(s).

And your right too with the company behind VirtualBox. Indeed VirtualBox is openly licensed and free of charge for private use. Ever heard of proxmox? I heard of in a podcast about the attacks by Open AI to Hugging Face aso. Proxmox was used there to build virtual machines so I guess it's free of charge.

Never heard of promox before. Just looked at it shortly but seems it is not an as easy to use program like MAMP is. I'll add it to my list to try in case I really need a MAMP replacement.

1.6.4 is old but I got stuck on my way to 1.6.8... After successfully moved to the new machine now, I'll go on.

Actually an update to 1.6.8 should not be much of an issue despite some changes. But each system is different…