Error 20400

also make sure you have an updated default browser that's not opera.

I've moved this from the Using the Community forum (which is the forum for issues using the forums) to the Account, Payment, & Plan forum.

Scroll down here to see a list of the forums:
https://community.adobe.com/

See here:

https://helpx.adobe.com/x-productkb/policy-pricing/activation-network-issues.html#test-connection