dwinden on "[Plugin: iThemes Security (formerly Better WP Security)] HTTP ERROR 500"

@Mehrdad32

Just to determin whether any of the 2 settings mentioned earlier is causing the ERROR 500 msg you can manually remove the corresponding lines from the .htaccess file.

First manually remove the many many many "HackRepair.com Blacklist" lines.

If that does not make any difference remove the 2 "Disable PHP in Uploads" lines too.

Both of these settings add a RewriteCond/RewriteRule to the .htaccess file with a regular expression which could be causing your issue.

dwinden