Unknown sign in prompt inside AVD pointed to Azure File Share

\\<name>.file.core.windows.net\data is an Azure Files SMB share being accessed by UNC path. Azure Files supports direct access by UNC path without mapping it to a drive letter, so it can appear in net use even when no visible drive mapping was configured for that user.

That means the prompt is coming from some process in the AVD session trying to reach that Azure file share, not necessarily from an AVD drive mapping.

Relevant points:

1. Azure Files can be accessed directly as \\storageaccountname.file.core.windows.net\myfileshare.
2. Windows can prompt for network credentials when something tries to open that UNC path.
3. If the share is being accessed with identity-based authentication and authentication or authorization is not valid, access can fail with repeated credential prompts or access denied.

For the specific net use entry:

• file.core.windows.net identifies Azure Files.
• data is the Azure file share name.
• Because it shows in net use, there is an SMB session/connection to that share from the user session.

To identify what is triggering it in AVD, check:

1. Logon scripts or Group Policy drive/share connections.
2. FSLogix or profile/container redirection settings that reference an Azure Files UNC path.
3. Application shortcuts, recent files, startup apps, or Explorer quick access items pointing to that share.
4. Any script or app running in the user session that opens \\<name>.file.core.windows.net\data directly.

If users are being prompted repeatedly, common AVD causes include:

1. Conditional Access sign-in frequency mismatch between the Azure Virtual Desktop app and Windows Cloud Login app.
2. Legacy per-user MFA enabled together with Conditional Access.
3. Missing Conditional Access policy for the Windows Cloud Login app.

If the Azure file share is intended to use AD-based access, the documented checks are:

1. Verify the client is domain joined.
2. Verify port 445 connectivity.
3. Run Debug-AzStorageAccountAuth to check AD object, Kerberos ticket, Microsoft Entra sync, and RBAC/share-level access.
4. If needed, test mounting with the storage account key to confirm whether the problem is identity-based authentication.

• Mount SMB Azure file share on Windows
• Troubleshoot single sign-on and Conditional Access for Azure Virtual Desktop
• Troubleshoot Azure Files identity-based authentication and authorization issues (SMB)