It seems latest Windows Update updated .Net to 4.7.2 .
4.7.1 can not be installed because I already have 4.7.2
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SourceTree.exe - This application could not be started.
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This application requires one of the following versions of the .NET Framework:
.NETFramework,Version=v4.7.1
Do you want to install this .NET Framework version now?
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Yes No
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