Q. Why am I getting an error Bad HTTP response (302 Found)?
A. Most common cause for this error is that the URL you entered redirects to another URL.
Please check this by going to the URL you entered in ManageWP and check if the URL in the address bar of your browser changes. If it does, you need to remove this redirect.
The URL you enter when adding the site to ManageWP needs to point to your WordPress homepage. Check you WordPress admin settings for the Home URL and make sure it matches your URL.
Other causes include using Login Lock plugin which is covered in known issues.