Error.. There is currently a configuration error in the Apache configuration file.

[vanessafan]

I can't change the username in WHM

"Error.. There is currently a configuration error in the Apache configuration file. User name change aborted."

I've rebuilt the httpd.conf file and it is fine

/scripts/rebuildhttpdconf
Built /usr/local/apache/conf/httpd.conf OK

I've googled this and some people were saying that the default memory should be set to 256 MB in WHM->Tweak Settings, and it is already set to that.

What's wrong?
Thanks

[cPanelTristan]

Can you check /usr/local/cpanel/logs/error_log when trying to change the username to see if it reports any other error there?

tail -fn0 /usr/local/cpanel/logs/error_log