The fact that users can access on-premises SMB shares using WHFB and Cloud Kerberos Trust implies that Cloud Kerberos itself is functioning correctly. The issue appears to be specific to Azure Files authentication rather than Kerberos in general.
Check which Kerberos ticket is being obtained. On an affected Entra-joined device, after the user signs in with WHFB, run klist and klist cloud_debug. You should see a Cloud TGT as well as a service ticket for the Azure Files SPN (typically cifs/<storageaccount>.file.core.windows.net) when the share is accessed. If the service ticket is not issued, the problem is occurring before Azure Files authentication.
Verify that the storage account's AD DS configuration is healthy. Confirm that the storage account has the correct domain information (Get-AzStorageAccount -ResourceGroupName <RG> -Name <StorageAccount> | Select AzureFilesIdentityBasedAuthentication), that the AD computer object representing the storage account still has a valid password and SPNs, and that the Kerberos encryption types match your domain policy. AES-256-only is supported, but if domain controllers or the storage account object have inconsistent encryption settings, Kerberos can silently fall back to prompting for NTLM credentials.
The fact that domain\username works but UPN does not indicates Windows Credential Manager is falling back to legacy SMB authentication rather than using the user's existing Kerberos session. If Kerberos were being used, users should not be prompted at all. It might worth checking whether the SMB client is attempting Kerberos by capturing Microsoft-Windows-SMBClient/Connectivity and Microsoft-Windows-Kerberos-Key-Distribution-Center event logs while reproducing the issue.
Another potential cause might be DNS or SPN resolution. Ensure clients are connecting using the storage account FQDN (\\storageaccount.file.core.windows.net\share) and not via an alias or DFS namespace unless SPNs have been configured appropriately. Kerberos requires the service principal name to match exactly.
You might want to also check whether this is an issue with Device Preparation Policy deployments. Compare an affected device against a working Entra-joined device by looking at:
-
dsregcmd /status
-
klist cloud_debug
-
klist tickets
-
gpresult /r (to confirm no legacy credential or Kerberos policies differ)
-
Get-SmbConnection after attempting access
- Event Viewer under Applications and Services Logs → Microsoft → Windows → SMBClient and Kerberos.
If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.
hth
Marcin