vrunda.kansara

The file types that needs to be allowed have its own settings under :
Dashboard >> Network Admin >> Settings >> Network Settings
Scroll down to Upload Settings and add or remove file types from the “Upload file types” field.

You can simply disable this filtering by using following code. You have to add it in your wp-config.php.

define(‘ALLOW_UNFILTERED_UPLOADS’, true);

Note: Now you have allowed upload for all types of file on your blog. This may lead to serious security issues. Take care that any file uploaded on the server can be executed if it is not managed properly.