Comment 8 for bug 1659567

There is no way that I'm aware of in any current Squid.

The check is a generic validity check used for all ACLs. Whether it is 'harmless' depends on future events at the time of checking. So just silencing or ignoring would leave a lot of nasty misconfigurations quietly accepted.

That said; for an automated rotate 2>/dev/null seems reasonable. These types of thing should be caught and fixed on the previous startup or manual rotate attempts.

Long-term I think we are going to have to add an explicit flag to indicate whether an ACL is allowed to be empty or not.