“The following solution cannot be loaded because the .NET Framework 5.5 is not installed Merlin.vsto” when opening Excel after installation.
Locate the folder:
C:\Program Files(x86)\Common Files\Microsoft shared\VSTO\10.0
Where 10 is the Excel version number so may be different on your pc
Rename the file VSTOInstaller.exe.Config to VSTOInstaller.exe.Config.old