You may see this message on some servers when you try to save an event. It arises because you have configured JEvents to check for overlapping events when you save a new or changed event. If you don't need this on your site then disable this option - if you do want to block overlapping events then please read on:
It is usually caused by the fact that your server cannot run the script components/com_jevents/libraries/checkconflict.php usually because you have installed a security setting that block all php scripts apart from the main index.php script.
This could be caused by:
- Akeeba AdminTools - in which case make an exception in the AdminTools settings to allow the script http://www.yoursite.com/components/com_jevents/libraries/checkconflict.php to run.
- File permissions - the script may have the wrong ownership or permissions. In which case please check these for the file components/com_jevents/libraries/checkconflict.php
- Htaccess - you may have a deny setting for php scripts outside the index.php file. In which case please add an exception for this script.
Technical background
The checkconflict script is a slimmed down version of the core index.php script that doesn't load a lot of the core Joomla CMS features like the menus and the main router. This makes it a LOT faster to check for overlapping events before passing control of the script on to the main event saving routines