You might see the Activation wizard appear unexpectedly, and Office fails to activate over the Internet with the following error message:
This product cannot be activated because the product key is not valid.
Select your version of Office below for help with this error message.
If you see this message, this means that your Office product key has been blocked and will no longer work.
If your Office product key doesn’t work, or has stopped working, you should contact the seller and request a refund. If you bought a product key separate from the software, it’s very possible the product key was stolen or otherwise fraudulently obtained, and subsequently blocked for use. Unfortunately, there are many dishonest sellers who offer stolen, abused, or otherwise unauthorized Microsoft product keys for sale. Sometimes these product keys are printed on counterfeit labels or cards with a download link to Microsoft software, and sometimes they’re distributed with software media that is unauthorized for resale, such as promotional media, original equipment manufacturer reinstallation media, or other Microsoft program-specific media.
If you're not able to get a refund from the original seller and you want to buy Office, select Buy Office below to compare prices and buy Office from the Microsoft Store. Or, select Try for free to start a free trial of Office 365.
Buying a product key?
If you're shopping for Office product keys elsewhere, we recommend that you review our tips for safer shopping to make sure you're buying genuine Microsoft software. Be sure to read the tip called Beware of Product Keys Sold Separately if you want to buy a product key online.
If you have a current Office 365 subscription, here's how to fix this issue:
Close all Office apps.
Go to Services & subscriptions and sign in with your Microsoft account.
Under your Office 365 subscription, select Installs.
Under PC/Mac installs used, select Sign out of Office for the device where you're getting this error. For help, see Deactivate an Office 365 install.
In Windows, right-click the Start button on the lower-left corner of your screen, and then select Run.
In the Open box, type C:\ProgramData\Microsoft\Office\Heartbeat and then select OK.
File Explorer opens. On the View menu, select Hidden items.
In File Explorer, delete HeartbeatCache.
Open an Office app, and sign in with your Microsoft account when prompted.