What version of ERA do you have installed? Is it 6.1.444.0? Could you post a screen shot of the error you're getting? Have you checked the trace log for more details about the error? Do you connect through a proxy server? If so, is it properly configured in the advanced ERAS setup?
I'm running into the same issue. Currently ERA is 6.1.144.0, we do use a proxy. The proxy is set on the server in Windows and also set in ERAS setup. The error in the log is
2015-09-04 18:25:34 Error: CSystemConnectorModule [Thread 808]: UpgradeInfrastructure: Task failed: GetFile: Cannot connect to host 'repository.eset.com'