I was having trouble with a new self-hosted site i created when I tried to connect JetPack to my wordpress.com account. I kept getting this error:
Invalid request, please go back and try again. Error Code:invalid_client Error Message: Unknown client_id.
I also got this code when I tried to manually add the site to the My Sites panel in my WordPress.com account. From reading forum posts about this error, it also seems that it can occur when you try to reactivate the Jetpack plugin, after it has been deactivated for updates, etc.
I found this solution to the problem:
- Deactivate and Delete Jetpack plugin
- Go to your PHPMyAdmin
- Run the SQL Query :
SELECT * FROM `wp_options` WHERE `option_name` LIKE '%jetpack_%'
- Delete the items that start with the option_name
- Download and Install Jetpack.
It is really quite simple to do, and it worked perfectly.