Microsoft 365 SAML prompt fails / blank window VPN

[DavidLaz]

Good morning,

We recently had this issue whereby AnyConnect was set to authenticate via 365 SAML in a hybrid environment. All machines had no issue with the rollout and testing, apart from one Windows tablet, which presented this after clicking on "Connect":

And the logs reporting "user credentials prompt cancelled".

To clear this, simply navigate to "Preferences" and uncheck "Block connections to untrusted servers" then retry. You should get the stock MS auth prompt:

Cheers

Regards,
DavidLaz

[Mloraditch]

If that is the box you had to uncheck to make this work, you likely have some sort of certificate issue on the the tablet. What specifically is harder to tell. If you are using a custom or the auto generated, perhaps the right root is not installed or up to date on that tablet. If you are doing something self signed it would need to be present in the tablets roots.

There could be some other corner case issues, but you'd have to look at the logs on the device.

[DavidLaz]

Yeah, that was one of my suspicions too. This is just a workaround.