Several factors can contribute to the occurrence of Error 120:

Using the Microsoft Program Install and Uninstall troubleshooter (formerly FixIt) to clear corrupted entries.

If the license file remains "incomplete," uninstall any previous versions or evaluation copies and perform a clean installation.

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For older versions like ETABS 2016, users often encounter this error when the license has technically expired. Below are the standard and community-recommended steps to fix it:

For standalone licenses locked to a USB key, the lservrc file must be accompanied by a properly installed and recognized USB key driver.

You are attempting to use a license file from an older version of ETABS with a newer version (e.g., trying to use an ETABS 2016 license on ETABS v20).

How to Fix ETABS License Not Recognized Error 120: A Comprehensive Guide

The server is running an older version of the Sentinel RMS License Manager that is incompatible with newer versions of ETABS. Step-by-Step Solutions to Fix Error 120 1. Restart the Sentinel RMS License Manager Service

ETABS is a finite element-based software developed by Computers and Structures, Inc. (CSI) for the analysis and design of buildings and other structures. The software requires a valid license to operate, which can be either a standalone license or a network license.

Antivirus or Windows Firewall blocking the license verification processes. Step-by-Step Solutions to Fix Error 120

For detailed guides on specific versions, you can refer to the official CSI Knowledge Base or check support videos on Are you using a standalone license on a single PC or a license managed by a server?