I have been installing OpenCart Mobile Framework to a lot of customers lately. This led me to interact with various servers and configurations, but I was most amazed when everything was supposed to work fine but It didn’t.
This is when I came to a problem. Sometimes, in the rarest of cases, installing vQmod makes your server show an “internal server error 500” giving you absolutely no clue what do you have to do. Turns out in this case the solution is simple: just remove the vqmod/.htaccess file and everything should work fine.
And before I go here is an Apache troubleshooting rule of thumb for you:
always edit .htaccess files one by one, and test after each edit.
Usually they are the most common cause of http 500 error.
Hope this helps!