If the EAC says your key is invalid, the most reliable workaround is using the . Enter your Exchange Server product key | Microsoft Learn
: For persistent errors, clearing the registry of previous key attempts using slmgr.vbs /cpky exchange 2019 product key invalid
If you installed the evaluation edition and allowed the 120-day grace period to lapse without entering a key, the server enters a "not licensed" state. In this state, the product key input mechanism may become temperamental or refuse to accept any key, requiring a reinstall. If the EAC says your key is invalid,
# Provide specific advice based on common errors if ($_.Exception.Message -like "*invalid*") Write-Host "ADVICE: Double-check the characters. Common mistakes are 0/O, 8/B, G/6." -ForegroundColor Yellow # Provide specific advice based on common errors if ($_
Get-ExchangeServer | fl Name, Edition, AdminDisplayVersion, IsExchangeTrialEdition Use code with caution. Copied to clipboard 3. Check for Trailing Spaces
: If you are using a Volume License key, ensure you aren't accidentally trying to apply a KMS client key as a permanent product key. Microsoft Community Hub Expected Behaviour