We've received multiple reports regarding issues with activating, reinstating, upgrading any types of subscription. This is affecting different kind of subscriptions (Premium, Duo, Family, Student, etc...).
The error message is the following:
Thanks for your patience while we looked into this issue.
We’re happy to say that this should now be fixed for everyone! Just make sure to restart your device, clear your browser's cache and reset its history.
If you're still having trouble, make sure to post a new thread in the relevant help board here.