This error can be caused by a variety of issues but is most likely caused by a corrupt
.htaccess file. Check to see if there is an
.htaccess file in the directory where the error is being generated or any directory above in the tree. If so, temporarily rename the
.htaccess file and refresh the page. If the error does not reappear, the
.htaccess file is the issue. Repair the file or leave it disabled.
If you encounter further issues with the renamed
.htaccess file, revert its name, and try restoring it from a backup.
Most of the time
.htaccess issues are caused by trying to overwrite PHP settings, being uploaded in binary format or permissions issues.
Be sure to upload
.htaccess files in ASCII mode
Set the permissions to 644, which makes it usable by the server, but prevents it from being read from a browser.
If you are trying to make changes to PHP settings, be sure to make changes to your PHP initialization file.
For more information see: