Set-ExchangeServer -Identity "SERVERNAME" -ProductKey "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX" Then restart the Exchange services or reboot.
Run the following command in as Administrator: exchange 2019 product key invalid
Fix: "Product Key Invalid" Error When Installing Exchange Server 2019 Please enter a valid product key
If the issue persists after trying the above, open a support case with Microsoft Volume Licensing Support. For permanent installations, you must use a genuine
When attempting to install Microsoft Exchange Server 2019 (typically the Cumulative Update or the RTM version), you receive the error message: "The product key is invalid. Please enter a valid product key." This occurs even when using a legitimate Volume License (VL) key or attempting to use the free Exchange Server 2019 Standard Edition trial key ( H7M39-... ).
Microsoft has phased out the generic 120-day trial key for Exchange 2019. For permanent installations, you must use a genuine VL key or contact your Microsoft licensing partner.