I just today I tried to connect to my work network from home using the Cisco AnyConnect client, for reference I’m using AnyConnect 3.1.05182 on Windows 8.1, and was unable to. I was immediately presented with an error before even being asked for a username and password, which said something was wrong with the client, as it hadn’t really had time to start any proper negotiations with the ASA.
A little bit of Googling revealed that the problem might have come from a recent Microsoft update, dated just a few days ago. I had noticed my machine downloading a few updates of late, and I’m nowhere near as diligent with testing updates on my personal machine as I should be, or as I am on any work related systems.
While Cisco have said ultimately the fix has to come from Microsoft, there is a workaround until a permanent fix is produced;
On the final test when the AnyConnect client opens again, you then find that you’re able to connect normally again. If you have Cisco support it would probably be valuable opening a TAC case and mentioning case number #115021112390273. This bug does also affect Windows 7 when IE11 is installed, and the same fix should work there too.