Resolving Proxy Authentication Issues for Asset Transformer Toolkit Package

Summary: This article addresses issues with adding the Asset Transformer Toolkit package in Unity when behind a company firewall. The primary cause is the proxy server blocking the download due to missing credentials. The resolution involves enabling proxy auto-configuration or manually specifying proxy settings in environment variables. Additionally, adding certain Unity domains to the proxy's exception list can resolve the issue.

Symptoms:

• Error adding Asset Transformer Toolkit package
• Workstation behind company firewall
• Issue occurs only on Windows
• Error message: Proxy authentication failed: missing credentials

Cause: The issue arises because the company's proxy server requires authentication credentials that the Unity Package Manager is not providing, thereby blocking the download.

Resolution:

1. Enable Automatic Proxy Configuration:
   • Modify the services-config.json file at %PROGRAMDATA%\Unity\config\services-config.json.
   • Set enableProxyAutoconfig to true.
2. Add Unity domains to the proxy's exception list:
   • packages.unity.com
   • download.packages.unity.com
   • packages-v2.unity.com
   • Full list: Unity Proxy Exception List.
3. Manually specify proxy credentials:
   • Configure proxy credentials in the Windows Credential Manager.
   • Or set proxy environment variables as outlined here: Unity Proxy Environment Variables.
4. Consult your IT team for further assistance with internal network configurations if needed.