Within Citrix Studio, In Licensing Tab -> When you try to change the license server, you may get untrusted message -> "License server unavailable" 



Error received from command: Get-LicCertificate  -AdminAddress "https://hostname or FQDN of license server:8083", Error:
Name : Get-LicCertificate
Exception : System.InvalidOperationException: CommunicationError
   at System.Management.Automation.MshCommandRuntime.ThrowTerminatingError(ErrorRecord errorRecord)
PositionMessage :
                + CategoryInfo : InvalidOperation: (Get-LicCertificate:String) [Get-LicCertificate], InvalidOperationException
                + FullyQualifiedErrorId : Citrix.PowerShell.LicensingAdminStatus.CommunicationError,Citrix.Licensing.Admin.SDK.Commands.GetLicCertificateCommand

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Couldn’t find http string mapping to port 80 in the services file under C:\Windows\System32\drivers\etc\services 

The below line needs to exist in services file.

http               80/tcp    www www-http           #World Wide Web

 

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Problem Cause

http string mapping to port 80 missing in the services file