Can you tell us what it says when you press the "More Info" button on that message box? That will help us narrow down exactly where the error is happening.
Skyline message boxes now have a copy button located in the lower left corner. If you press that, it will copy the message text, as well as the more info, onto the clipboard.

I imagine the error you saw was just a temporary internet problem, but if it does happen to you again, then please do send us that full message text so that we can improve our error handling in this area.

I am going to guess that you are on Windows 7 and the error is pertaining to the absence of .NET 4.7.2

We are working on this. In the meantime, you can go to the Skyline-daily installation page and click through the installation manually, and that should repair your installation, walking you through installing .NET 4.7.2

http://skyline.ms/daily.url

Hopefully, we can find a better solution soon.

--Brendan

Dear Nick, Dear Brendan,

Here is the message (indeed as Brendan expected):

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Skyline-daily
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Failed attempting to check for an upgrade.
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OK More Info
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System.Deployment.Application.CompatibleFrameworkMissingException: Unable to install or run this application. This application requires Version 4.7.2 Full or other compatible .NET Framework.
   at System.Deployment.Application.PlatformDetector.VerifyPlatformDependencies(AssemblyManifest appManifest, AssemblyManifest deployManifest, String tempDir)
   at System.Deployment.Application.DeploymentManager.DeterminePlatformRequirementsCore(Boolean blocking)
   at System.Deployment.Application.DeploymentManager.DeterminePlatformRequirements()
   at System.Deployment.Application.ApplicationDeployment.CheckForDetailedUpdate(Boolean persistUpdateCheckResult)
   at pwiz.Skyline.UpgradeManager.AppDeploymentWrapper.CheckForDetailedUpdate() in c:\proj\pwiz_x64\pwiz_tools\Skyline\UpgradeManager.cs:line 316
   at pwiz.Skyline.UpgradeManager.updateCheck_DoWork(Object sender, DoWorkEventArgs e) in c:\proj\pwiz_x64\pwiz_tools\Skyline\UpgradeManager.cs:line 104
---------------------------
Many thanks,
Sara