Get the Office Deployment Tool from Microsoft .
Completely remove the retail version of Office 2019. Get the Office Deployment Tool from Microsoft
If you need to move from a retail installation to a volume license, you can try the following methods: Get the Office Deployment Tool from Microsoft
The most reliable way to ensure you have a Volume License version is to install it correctly from the start. Get the Office Deployment Tool from Microsoft
The error message typically occurs when using third-party activation scripts or conversion tools (such as KMS_VL_ALL or C2R-R2V-AIO ). This specific error indicates that the automation script found a "Click-to-Run" (C2R) retail installation but was unable to swap its licensing certificates for Volume License (VL) versions required for KMS activation. Why This Error Occurs The conversion process fails for several common reasons: