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Version 7.3.51110 of the Microsoft Threat Modeling Tool (TMT) was released on November 10 2025 and contains the following changes:
- Added a new safeguard that prevents users from saving
.tm7and.tb7threat model files in the application's installation directory.- When attempting to save files in the install directory, the tool now prompts users to select an alternative location, such as the user's Documents folder.
- The application remains open until the files are successfully moved out of Threat Modeling Tool's installation directory.
- This change was introduced to prevent accidental data loss after application updates when files are stored in the application directory. This ensures threat models are saved in user-accessible locations.
- Bug fixes
- Accessibility fixes
Known issues
Errors related to TMT7.application file deserialization
Issue
Some customers have reported receiving the following error message when downloading the Threat Modeling Tool:
The threat model file '$PATH\TMT7.application' could not be deserialized. File is not an actual threat model or the threat model may be corrupted.
This error occurs because some browsers don't natively support ClickOnce installation. In those cases, the ClickOnce application file is downloaded to the user's hard drive.
Workaround
This error will continue to appear if the Threat Modeling Tool is launched by double-clicking on the TMT7.application file. However, after bypassing the error the tool functions normally. Rather than launching the Threat Modeling Tool by double-clicking the TMT7.application file, users should utilize shortcuts created in the Windows Menu during the installation to start the Threat Modeling Tool.
System requirements
- Supported Operating Systems
- .NET Version Required
- .NET 4.7.1 or later
- Other Requirements
- An Internet connection is required to receive updates to the tool and templates.
Documentation and feedback
- Documentation for the Threat Modeling Tool is located on learn.microsoft.com, and includes information about using the tool.
Next steps
Download the latest version of the Microsoft Threat Modeling Tool.