Can you please give a link to a page on your site, where I can easily find a CF7 form, so I can test it.
Moderator
Jan Dembowski
(@jdembowski)
Forum Moderator and Brute Squad
Link moved to the first post.
Tested. Looks like a JavaScript conflict on send but could also be very slow email sending – it gets there in the end.
Note: JS works quickly for required field validation.
Try switching temporarily (nothing will be lost when you switch back) to a WP default theme & disable all plugins other than Contact Form 7 to see if the problem goes away.
If it does you can switch back to your theme & re-activate each plugin one by one to see when the problem occurs.
As a temporary stop gap measure you may consider stopping Contact Form 7 from loading any JavaScript – see Loading JavaScript and Stylesheet Only When it is Necessary
You will lose all of CF7’s Javascript functionality which is very important.
You can also use Contact Form 7 Controls to disable all Contact Form 7 JavaScript via a simple option if want to avoid working with your wp-config.php file.
