Error 500 (internal server error) is very frequent in webs whose control panel is Webuzo, and has SUphp activated. To solve the 500 error in Webuzo, you must do the following.
1- Check the permissions of the files and folder are as follows.
755 for folders,
644 for the files.
2- Check that the files are under the user’s property
3- Finally the option number three, which generally is the problem, you just have to remove the apache from the Webuzo Panel and re-install it.
Doing these steps, surely the problem is solved, we recommend first apply step three, as stated above, this is generally the problem.