(Note: Microsoft "Support" told me to turn off "Try the new admin center" so the images show different layouts.)
When I click "extend end date", I have the option to enter a new license key or to add a credit card. I don't have a new license key to enter, but since it's already "free", I shouldn't have to buy a new subscription to get a new license key.
When I try to select "Add a payment method", I get the error message, "We are sorry. An unforeseen error has occurred. (CV: ZIE29yAwbkqyVBJm.0.9)". Googling the error produced zero helpful results. Please advise.


