I've been reciving this error when trying to login via Pulse. I'm not seeing anything in the logs on my end.
I understand the issue, suspect the issue with pulse and host checker, not sure whether you have enabled Hostchecker however the below two knoeldegebase links has more or less majority of pulse issues covered, please go through this. I am sure it will help you.
if the above KB's not resolving your issue, its important for us to look in to user access logs on IC and pulse client side logs.
Note: If I have answered your questions, you could mark this post as accepted solution, that way it could help others as well. Kudo will be a bonus thanks!
If someone is facing this issue again in Jan 2018 on windows OS, you need to uninstall latest security update from microsoft, which is following.
The problem is with WIndows 8.1 and Windows 10 machines that have updated to Microsoft's January 3rd updates and the Pulse Secure uses Host Checker at realm or role level. It stops the Host Checker call out to happen and rejects connection.
What we did:
Downloaded the 184.108.40.2063 Pulse Secure desktop client installer package
uploaded to our MAG2600 (running 8.2R9 (build 58917))
Advised all clients to connect to their Pulse Secure desktop clients for the upgrade.
-- then advised if it failed, they needed to uninstall and redownload the Pulse Secure desktop client from our VPN home page.
Worked for our folks.