App-V Support Tip: Publishing Server URL is unreachable after upgrade to 5.1

After upgrading App-V 5.0 Management and Publishing servers to App-V 5.1, you may encounter a problem where publishing no longer function properly and the following issues appear:

- Accessing the Publishing URL in Internet Explorer from directly on the Publishing Server (e.g.http://localhost:82, where 82 is the port assigned to the Publishing Server Service) generates the following error message:

The website cannot display the page

- The event below is seen in Event Viewer\Applications and Servers logs\App-V\Server-Publishing-Private\Debug:

Failed to pre-load publishing metadata. 

Message: Object reference not set to an instance of an object. 

Details:  

Stack Trace: 

   at Microsoft.AppV.Server.Publishing.PublishingMetadataSerializer.PackageSerializer.Load(XElement pkgElement, PublishingMetadata& data) 

   at Microsoft.AppV.Server.Publishing.PublishingMetadataSerializer.RootSerializer.Load(XmlReader reader) 

   at Microsoft.AppV.Server.Publishing.PublishingMetadataSerializer.LoadFromFile(String filePath) 

   at Microsoft.AppV.Server.Publishing.DataManager.ProcessRawMetadata() 

   at Microsoft.AppV.Server.Publishing.DataManager.PreLoadPublishingMetadata() 

   at Microsoft.AppV.Server.Publishing.DataManager..ctor()

To know about the cause and the resolution check the below Microsoft Technet link.

http://blogs.technet.com/b/appv/archive/2015/10/22/app-v-support-tip-publishing-server-url-is-unreachable-after-upgrade-to-5-1.aspx