Error ID 6027 - MS Filtering Engine Update process was unsuccessful in contacting the Primary Update Path. Update Path: http://forefrontdl.microsoft.com/server/scanengineupdate

Hello. 

I have an installation of Exchange 2013 SP1, and since a few days I continually receive this error message.

MS Filtering Engine Update process was unsuccessful in contacting the Primary Update Path. Update Path: http://forefrontdl.microsoft.com/server/scanengineupdate

Any solution?

Thanks.

MCSA: Windows Server 2008