License key file validation failed (5505051)  occurs when you attempt to install an invalid license file (such as SGOS 5 Edition) on a ProxySG appliance running SGOS 6.x. Sometimes the license needs to be Updated through the LCAMS server Update License for the license to include the updated component.

Note: If the ProxySG is not under a valid support agreement, Update License will not add the SGOS 6.x component.