VMware introduce NTLM authentication on App Volumes v2.10. It is used to verify the user, computer, and the domain of the agent when it makes HTTP requests to the App Volumes Manager.

Unfortunately, this NTLM authentication method causing random Authentication failure when App Volumes Agent trying to communicate to Manager. It generally shows the error message –

Error:
App Volumes Message
Error from Manager <dns name> (error code 401):
NTLM Authentication failed for: <Domain\user>
Virtualization is disabled
Solution:
Disabling NTLM authentication fixed the error 401 issue. To allow or stop the HTTP request from proceeding, a system environment variable need to modify.

• On the App Volumes Manager machine, open Windows Explorer.
• Right-click My Computer.
• Click Properties > Advanced System Settings > Environment Variables.
• In the System Variables panel, click New. The New System Variable window appears.
• Enter AVM_NTLM_DISABLED in the Variable name text box.
• Enter 1 in the Variable value text box.
• Restart the App Volumes Manager service.