Etabs License Not Recognized Error 120 Online

Fixing the “License Not Recognized (Error 120)” in ETABS: A Step-by-Step Guide

Few things are more frustrating than sitting down to meet a tight deadline, launching ETABS, and being greeted by the dreaded “License Not Recognized (Error 120)” message.

This error essentially means that the Licensing Service (usually the Computers and Structures, Inc. (CSI) License Manager) cannot communicate with your license file or server. Before you panic and reinstall everything, know that this is a common issue with a straightforward fix.

Here is your complete guide to diagnosing and resolving Error 120 in ETABS. etabs license not recognized error 120

5. Troubleshooting Performed

| Step | Action Taken | Result | |------|--------------|--------| | 1 | Restarted ETABS and computer | Error persisted | | 2 | Verified that CSI License Manager service is running (services.msc) | Service was [running / stopped / missing] | | 3 | Checked firewall rules for ETABS and lmgrd.exe | [Blocked / Allowed] | | 4 | Temporarily disabled antivirus software | Error [resolved / persisted] | | 5 | Verified license file (lservrc) exists in C:\ProgramData\CSI\Licenses\ | File [present / missing] | | 6 | Checked USB hardware key (if applicable) | Key [detected / not detected] | | 7 | Ran ETABS as Administrator | Error [resolved / persisted] | | 8 | For network license: Pinged license server IP | [Successful / Failed] |

2. Problem Description

Upon launching ETABS, the following error message appears: Fixing the “License Not Recognized (Error 120)” in

"License not recognized. Error 120"

The software initialization fails immediately after this message. No further functionality is accessible. The issue is reproducible on every launch attempt. "License not recognized

Solution 3: Compatibility Mode and Admin Rights

Sometimes, Windows updates can change permission settings, preventing the software from reading the license registry.

Right-click the ETABS icon on your desktop.
Select Properties.
Go to the Compatibility tab.
Check the box for Run this program as an administrator.
Optionally, try running the program in Compatibility Mode for Windows 8 or 7 if you are on an older build of ETABS on Windows 10/11.
Click Apply and try launching the program again.

Step 7: The "Loopback Adapter" Workaround (For IT Professionals)

This is a niche fix for computers that intermittently lose network connection or use VPNs. Installing a Microsoft Loopback Adapter creates a virtual, permanent network card. The license binds to this adapter, so it never "changes."

Open Device Manager → Action → Add legacy hardware.
Select "Install the hardware that I manually select" → Network adapters → Microsoft → Microsoft Loopback Adapter.
Install it. Do not configure IP settings (leave as DHCP).
Restart the Sentinel RMS service and re-run ETABS.