Exchange 2019 Product Key Invalid

via an elevated Command Prompt may help, though this is primarily for Windows Server licenses. Microsoft Community Hub Are you using a Volume License Retail Key , and did you install the server as an Evaluation Get help with Windows activation errors - Microsoft Support

If PowerShell also fails, check for these common underlying issues: exchange 2019 product key invalid

Open the as Administrator and run:

Use the following command to see your licensing status: via an elevated Command Prompt may help, though

Troubleshooting "Invalid Product Key" in Exchange Server 2019 exchange 2019 product key invalid