thanks for the reply; when i delete groups and some users the error InvalidParameterException start occuring.

This is not the complete error message. Check the error log on the server. The error message in the log should be more detailed.

When deleting users or groups all the content added by the user or added to this group respectively should also get deleted automatically. But if you had some 3rd party plugin on your site and there was added some content handled by this plugin either by the user or the group you delete and at the time of deletion this plugin is not enabled, it could happen that this content is not deleted. So, there might remain some content that belonged to this user (or group) and this content now causes a problem even if it wouldn't get displayed anymore.

Without the complete error message it's difficult to say if the problem is caused by some content belonging to a disabled plugin. You would know best if you had some plugin installed that now is no longer available and might cause the problem. In this case it might help to add this plugin again at least temporarily to delete any content that's still there from this plugin. Or it might help to use the dbvalidator plugin (https://github.com/Elgg/dbvalidator) to clean up the database from faulty entries (if you try this plugin, first do a validate run only to see if there is anything the plugin can fix at all and if you would make a fix run do so only after you have made a backup of the database).

Elgg datalist

DATAROOT   F:/xampp/htdocs/elgg/data/

PATH F:/xampp/htdocs/elgg

Elgg_site_entity  http://127.0.0.1/elgg/

Modifier le fichier setting.php dans le répertoire elgg-config

http://learn.elgg.org/en/stable/admin/duplicate-installation.html#database-entries