Hi. I have some question.

An exception occurred while debugging the ExecutiveDashboard demo source code.

exception text : 
System.InvalidOperationException: 'An error occurred while processing this request.'
DataServiceTransportException: The request was aborted: Could not create SSL/TLS secure channel.
WebException: The request was aborted: Could not create SSL/TLS secure channel.



An error occurred while downloading and installing the ExecutiveDashboard demo app(setup.exe).

install.log : 
The following properties have been set:
Property: [AdminUser] = true {boolean}
Property: [InstallMode] = HomeSite {string}
Property: [NTProductType] = 1 {int}
Property: [ProcessorArchitecture] = AMD64 {string}
Property: [VersionNT] = 10.0.0 {version}
Running checks for package '.NET Desktop Runtime 6.0.1 (x64)', phase BuildList
Checking conditions before installer checks for command 'net6desktopruntime_x64\windowsdesktop-runtime-6.0.1-win-x64.exe'
Result of running operator 'ValueNotEqualTo' on property 'ProcessorArchitecture' and value 'AMD64': false
Result of checking conditions before installer checks for command 'net6desktopruntime_x64\windowsdesktop-runtime-6.0.1-win-x64.exe' is: No action
Running external check with command 'C:\Users\jmkim\AppData\Local\Temp\VSD29A9.tmp\net6desktopruntime_x64\NetCoreCheck.exe' and parameters 'Microsoft.WindowsDesktop.App 6.0.1'
Process exited with code 0
Setting value '0 {int}' for property 'NetCoreCheck'
The following properties have been set for package '.NET Desktop Runtime 6.0.1 (x64)':
Property: [NetCoreCheck] = 0 {int}
Running checks for command 'net6desktopruntime_x64\windowsdesktop-runtime-6.0.1-win-x64.exe'
Result of running operator 'ValueNotEqualTo' on property 'ProcessorArchitecture' and value 'AMD64': false
Result of running operator 'VersionLessThan' on property 'VersionNT' and value '6.1.0': false
Result of running operator 'ValueEqualTo' on property 'NetCoreCheck' and value '0': true
Result of checks for command 'net6desktopruntime_x64\windowsdesktop-runtime-6.0.1-win-x64.exe' is 'Bypass'
'.NET Desktop Runtime 6.0.1 (x64)' RunCheck result: No Install Needed
Launching Application.
URLDownloadToCacheFile failed with HRESULT '-2146697208'
Error: An error occurred trying to download 'http://demos.telerik.com/wpf/executivedashboard/ExecutiveDashboard.application'.

The same problem occurred with the SalesDashboard demo source code and app.

What caused the problem?