Slackware 14.1 Symptom: Apache not logging errors - Kate was my problem.
Just wanted to document this issue that caused me grief.
Apache wasn't logging errors or warnings even though my setup was the same as Slackware 14.0, 13.37.
Slackware 13.37 used Kate v3.5.5
Slackware 14.0 used Kate v3.8.5
Slackware 14.1 uses Kate 4.10.5
Sometime after Kate 3.8.5, they changed the way Kate saves the file to use a temporary file in the same directory as the one being edited, then MV the temp file over the old file. This causes the file to have the same owner:group as the user who saved it - regardless of what it was prior.
So on my machine I set the /var/log/httpd/error_log permissions to root:root-666 so I could have error_log open in Kate and as I'm developing I would clear the file and save it. With the owner changed Apache couldn't write to it.