I tried to update manually but no luck and as per the one article i have given time also but still it's not working..
i tried to force task update.
Menu --> Server Task --> Update Master Repository -->RUN.
when you cast you go to "Server Task LOG" and analyzes the possible error.
this is the error that i got "Failed to download file catalog.z from site update.nai.com:80" i understand the error log but how can i resolve it??
Can you navigate to the site from your ePO server, from a workstations?
Things to consider proxy, certificates.
I had the same issue with an ePO server running 5.1.1.
I resolved this by upgrading the server version to ePO 5.1.3.
As per the suggestion i have given more than one day... now it's working fine.... but didn't get exact solution for the issue.