Note: In some instances, the installation of .Net 4.6 will fail with a message similar to the following.
The cause of this issue is still under investigation by Microsoft. In the interim, customers that experience this issue can perform the following steps to work around this issue:
In Windows Explorer, navigate to the VSTO 10.0 folder. The path indicated in the error message should be something similar to C:\Program Files (x86)\Common Files\Microsoft shared\VSTO\10.0 or C:\Program Files\Common Files\Microsoft shared\VSTO\10.0.
In that folder, you should find a file named VSTOInstaller.exe.config. Rename it to VSTOInstaller.exe.config.old. (Ignore the warning from Windows about the file becoming unusable.)
Run the installation program again.
Undo the rename listed in step 2.