Hi,
This is one of the most common issues with Symantec Endpoint Protection Manager.
Below is the cause and the fix and let me know.
Cause of this issue:
IUSR account not present for the Local Machine & IUSR permissions.
Fix for this issue:
1. Created the IUSR account with Member of > User, Guest groups.
2. Added the new user to Symantec web site in IIS
3. Restart the IISAdmin services and SEPM Service.
4. Login to SEPM Console.
5. Issue Fixed