When trying to install the JCE content editor for Joomla version 2.2.6 in Joomla 2.5 it failed with HTTP Error 500 Internal Server Error. Directory permissions was not a problem and there was no problem installing other extensions.
- Download the JCE 2.2.6 zip archive to your computer.
- Unzip it to a local folder, called for example "jce"
- Upload the folder to your Joomla! tmp directory
- In the Joomla! backend, go to Extensions -> Manage extensions and go to the box for installation from a folder on the server.
- Enter the path where the uploaded folder containing JCE is uploaded, i.e. probably something like /var/www/mysitename/web/tmp/jce and click install.