Ensure your computer's date and time are accurate. In some cases, changing the PC date/number format to US (mm/dd/yyyy) is required for the licensing tool to process the activation correctly.
If you are using a standalone license, the most common fix is to refresh the activation status: Deactivate and Reactivate StandAloneKey.exe tool (found in the CSiLicensing etabs license not recognized error 120 work
Several factors can contribute to the occurrence of Error 120: Ensure your computer's date and time are accurate
In simple terms: Your computer knows a license should exist, but it cannot verify it due to port conflicts, corrupted configurations, or Windows services that have stopped working. Inc. (CSI). Supplementary Troubleshooting
Restart the activation process via the same License Assistant or activation tool provided by Computers and Structures, Inc. (CSI). Supplementary Troubleshooting