What are these 'client denied by server configuration' errors

Nextcloud version: 24.0.7
Operating system and version: Ubuntu 20.04
Apache or nginx version: Apache 2.4.41
PHP version: 7.4.3

The installation has been running stable for about a year.

I keep seeing this set of errors in my apache log several times a minute:

AH01797: client denied by server configuration: /var/www/nextcloud/index.php
AH01797: client denied by server configuration: /var/www/nextcloud/remote.php
AH01797: client denied by server configuration: /var/www/nextcloud/dav
AH01797: client denied by server configuration: /var/www/nextcloud/ocs/v2.php

Sometimes they are from an internal IP, sometimes from an external IP

What do they mean and does it mean I have a configuration error?

It is in your apache configuration. It can happen with VirtualHosts, if you are in a different virtual host for external access and for internal one (e.g. if you use name-based virtual hosts from outside with dyndns, then this might be different if you are in the local network just with the ip).

If it was running before, you should find out what you changed. If you updated something and the configuration changed, the old configuration was perhaps copied to keep a backup.

Good points. I’m definitely using virtual hosts by name. The same apache server does service and redirect to many sub-domains.

Internal clients have dns reflecting the internal IP. External clients have dns reflecting the external IP. I will do some testing with no internal clients connected and see if anything changes.

As for what has change, I don’t think anything other than normal updates but I can’t say that these errors were new as I wasn’t looking at the apache error log until recently since things seemed to be running OK.