It appears upgrading from Apache 2.2 to 2.4 changed the format of the errorlog file. Error logs used to show the remote client IP address.
Apache 2.2 errorlog: [Thu Aug 29 08:28:46 2019] [error] [client 50.57.61.20] message
Apache 2.4 errorlog: [Thu Aug 29 08:02:23.779174 2019] [:error] [pid 10036] message
Benevolently, Apache 2.4 added the ErrorLogFormat directive. So I specified:
ErrorLogFormat "[%{u}t] [%-m:%l] [%a] %M"
But the %a format string that is supposed to show "Client IP address and port of the request" is giving me blank.
Now the errorlog: [Thu Aug 29 11:13:13.281770 2019] [-:error] message
What I expected: [Thu Aug 29 11:13:13.281770 2019] [-:error] [204.115.145.100] message
The format string Client IP addresses are correctly showing up in the accesslog, which has a %h format string for "Remote hostname". There is no such format string for ErrorLogFormat.
We're running a dedicated Rackspace CentOS 7.6.1810 running, Apache 2.4.6.
