This error from Apache is typically caused by a very large cookie. In Apache the “LimitRequestFieldSize” directive sets this limit. The default is 8190 bytes. To change the file create a file at:
/etc/httpd/conf.d/custom.conf
or
/etc/apache2/conf.d/custom.conf
containing the desired change:
LimitRequestFieldSize 16384
Reload Apache after adding the file with:
/sbin/service apache2 restart
or
/sbin/service httpd restart
