My management console returns the following error after logging in. When I change from Home tab to Client I receive the following error "Failed to connect to the server. Make sure your server is running and your session has not timed out. if you can reach the server and cannot log on, make sure that you provided the correct parameters. If you are experiencing network issues, contact your system administrator. [0x80020000]. This is followed by another error "Invalid session [0x11010000]. Then I am logged off. This causes the Symantec Endpoint Protection Manager service to stop. Restarting the service allows me to log in again, however, the same errors are recieved and I am kicked out again.

I am using Symantec Endpoint Protection Manager version 11.0.6200.754 managing approximately 180 clients on three different domains and several different subnets. Has anyone ever experienced problems such as this and could provide me a solution?

Can you turn on debugging?

How to debug the Symantec Endpoint Protection Manager

You're on a old end of life version, may be time for an upgrade.

Best practices for upgrading to the latest version of Symantec Endpoint Protection 12.1.x

I suggest you can upgrade your SEPM 11.0.6200.754. to Latest SEPm 12.1.5.

SEPM 11.X going to EOSL on Jan -2015.

Does have you change anything in SEPM box ?

Please post the scm-server-0.log file.

I agree we need to upgrade. I have debugging turned on, however, I am not able to post the log file at this time. Is there a specific entry I should be looking for? We have recently added approximately 40 new clients. When I first installed the manager I dont believe we chose to manage more than one hundred and we now have around 180. Could that be an issue? I have also had problems because the c drive on my server sometimes falls below 2GB of free space. This usually prevented the signatures from updating. We now have over 4GB of space on the drive and I am still having issues. I am not sure what you are asking with the "Does have you change anything in SEPM box", what box? Thank you for your response.

You should be able to search on keywords of "error" "warning" "fatal"

Check the article

Logging on remotely to Symantec Endpoint Protection Manager 12.1 RU2 with an FQDN results in "Failed to connect to the server" and "ErrorCode: 0x80020000"

Thread

http://www.symantec.com/connect/forums/system-logsserver-activity-errorcode-0x80020000

I installed the manager on a different server because of the low disk space issue on the current server. I redirected a few of the servers and workstations to report to the new manager using the SylinkDrop feature and they all displayed as clients for more than a week. I tested all of this on my Quality Assurance System and it works just fine. Now however the new manager on the production system will not even allow me to log in. I get the error that the server is not available. Looking at the services the Symantec Endpoint Protection Manager Service is not running. I right click and choose start but it stops immediately with the message that some services stop automatically if not in use. I have tried reinstalling SEPM from the same disk used for the initial installation and no change. I have tried to repair the program through the Control Panel ADD/Remove programs and I get “Fatal error during installation”. Now I cannot log into either manager. Looking for a solution, please help.

Enble SEPM debugging:

How to debug the Symantec Endpoint Protection Manager

Post the scm-server.log file here is you need assistance reviewing it.