We are facing issue when trying to login into the gui of NDLP discover. Please refer the below screenshot for error and suggest a solution at the earliest.
Try logging into the appliance via ssh and issue "service stingray restart".
There's a recent version that had this issue with auth, so you may also want to make sure you're running the most current version.
Try rebooting the NDLP Discover..........
I also faced the same problem but in my case I am able to take ssh but not able to login & my device was showing as critical in System option.
Once I rebooted the problem was resolved...........
Try to restart the below mentioned services:-
service stingray restart
service jboss restart
service mysql restart
If still it doesnt work then u have to take help of support team...........
What version of NDLP Discover are you running ?
Was it a managed / unmanaged device?
This error sometimes occur in pre 9.3 version very often due to mysql issue.
Best to check if your stingray daemon is running or not first after reboot.