I moved my Joomla site to a new host powered by cPanel several days ago. Everything has been working smoothly till I find I cannot edit my post any more. Once I enter the article edition page, any operation will be result in 403 error.
Enable Joomla Site Debug Mode
At the beginning, I guess it could be a Joomla insite problem, something like the Article module doesn’t have enough permission. So I go to the system->global configuration, and switch to system tab, enable the debug system under debug setting.
After that, I repeat my operation by opening an existing article. Then when I click any buttons on the page, save or close, all I am facing with is a 403 forbidden error page. There is no any Joomla debug message. That means the request even doesn’t reach Joomla system.
Check Access Log
So I remotely login my host by SSH and watch the access log by tail command. After that, I repeat all my steps to repeat the 403 forbidden error. To be surprised, there is no access log at all. It seems the http post request even not reach the host. That becomes weird.
I have no idea what to do, but contact with my host administrator. After analyzing all jobs I have done, he suggested me to check web application firewall module, ModSecurity, in the cpanel. So I follow the instructions and disable modsecurity on my Joomla. All problems are solved.
According to it’s official document page, it is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx that is developed by Trustwave’s SpiderLabs.