1. Try clearing Java cache:
Control Panel->Java->General->Temporary Internet Files->Settings->Delete Files->Select Cached files and applets
For MAC OS X
Applications->System Preferences->Java->General->Temporary Internet Files->Settings->Delete Files->Select Cached files and applets
2. Self signed certificate is applied to the NetSight server
Temporary workaround prior to 8.03.xx for Windows Users
a. Stop Extreme Management Center server.
for linux OS - service nsserver stop
For Windows server service, see the following How to restart Netsight / Extreme Management Center services on linux or Windows Server Platforms
Navigate to the location of the nsserver.keystore file on the Extreme Managment Center Server
b. On Linux/Ubuntu, this will be /usr/local/Extreme_Networks/Netsight/wildfly/standalone/configuration
c. On Windows installations, this will be \Program Files\Extreme Networks\Netsight\wildfly\standalone\configuration
d. Rename the existing nsserver.keystore file "mv nsserver.keystore nsserver.keystore.old"
e. Restart the server (restarting the server service (i.e., “service nsserver restart” on Linux) should suffice.
f. Reconnect your client end system to the launch page or Extreme Management Center and launch the legacy clients
On startup, the server should detect the missing keystore file and generate a new one with an OOB certificate.
Currently, there is no ability to used certificates other than the default. This should be corrected in 8.03.xx release.