Why did the service stop working after renaming the NextCloud Pi host?

Question

linux

I installed NextCloud Pi on my 3rd raspberry
By default, the hostname is nextcloudpi
Recently I wanted to rename it to a more convenient name via /etc/hostname
After rebooting, the web interface gives an error:
Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.
Reverting the hostname to default doesn't help.
The apache service itself - works
Where to dig, where to look?

Answer 1

Take a look at /etc/hosts and config.php
There, too, you need to rename.
And for good it was necessary to use the standard functionalityhostnamectl set-hostname 'newname'