Microsoft Office 2019 activation key gives an error.

Error code 0xC004C060 means the Office product key is no longer valid and has been blocked on Microsoft’s activation servers.

This typically happens when:

• The key was stolen, abused, or fraudulently obtained and later blocked.
• The key was sold improperly (for example, a volume license or OEM/reinstallation key resold to consumers).

Since the error started after formatting the computer, the reactivation attempt is now failing because the key has been invalidated.

The only supported options are:

1. Contact the seller of the Office 2019 Pro key and request a refund or replacement.
2. If a refund is not possible and Office is still needed, purchase a new, genuine license directly from Microsoft or an authorized reseller. When buying separate product keys, review Microsoft’s tips for safer shopping and especially the guidance under Beware of Product Keys Sold Separately.

The blocked key itself cannot be reactivated by normal support channels.

References:

• Error code 0xC004C060 when activating Office
• "Product key is not valid" error when activating Office