Thanks for reaching out to the Community about this!
Can you let us know if you're still getting this error message?
If you've recently changed your country you'll need to add a payment method that matches your new country. This might be one of the reasons why you're not able to upgrade your plan.
On another note, are you trying to start your own plan or you're trying to join someone else's as a member?
We'll be on the lookout for your reply.
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