Delete residual folders in C:\Program Files\MITSUBISHI\GT Designer 3 and the %APPDATA% path mentioned above.
Check for the separate "GS Series Support" installer in your Mitsubishi Works 3 installation package. Summary Checklist Potential Issue Fix Action Right-click -> Run as Administrator Outdated Software Install latest GT Designer3 updates 1.2.3 Corrupted Config Delete AppData\Local GT files 1.2.4 Service Failure Restart MELSOFT License Service in services.msc
Right-click on the shortcut icon on your desktop. Select Properties . Go to the Compatibility tab. Check the box for Run this program as an administrator .
Windows Registry keys holding the license data have been corrupted, moved, or deleted. gt designer license not found
Mitsubishi includes a utility called .
Right-click the shortcut -> Select Properties -> Go to the Compatibility tab -> Check Run this program as an administrator -> Click Apply and OK . 2. Verify and Re-enter Your Product ID
Add the entire installation path folder as an exception. The default path is usually: C:\Program Files (x86)\MELSOFT\ Restart your computer and test launching GT Designer. Proactive Tips to Prevent Future License Errors Select Properties
The most straightforward solution is to re-enter your valid product ID. Navigate to your Windows Start Menu.
Navigate to C:\Users\ \AppData\Local or Roaming .
: A frequent cause is trying to open or create a project for a GS-series GOT (like the GS21) without having that specific support package installed. Windows Registry keys holding the license data have
| Check | Action | |-------|--------| | | For GT Designer3 (non-SoftGOT), a license is usually a USB dongle or software license certificate. | | Is the USB dongle inserted? | Check Device Manager → Universal Serial Bus devices → “MELSEC License Key” or similar. | | Is it SoftGOT? | SoftGOT requires a dedicated license (separate from GT Designer3). | | Did you install the License Manager? | Mitsubishi’s “License Manager” tool must be installed. | | Is License Manager service running? | Open Services → “MELSOFT License Manager” → Status should be “Running”. |
If the software opens without the error, you have a permissions issue.
Locate your original installer and run setup.exe in Modification Mode . Select "Change" or "Modify" .