After upgrading my laptop to Windows 10 I´ve installed WinMerge. The installation process was successful, without any error, but then when I started WinMerge the following error appeared:
C:\Program Files (x86)\WinMerge\WinMergeU.exe The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail.
Digged about it a little on Google and found that I was missing the installation of the Microsoft Visual C++ 2008 SP1 Redistributable Package (x86) – vcredist_x86.exe
I downloaded it from here: Download Microsoft Visual C++ 2008 SP1 Redistributable Package (x86)
Instaled it ( vcredist_x86.exe ), restarted the computer and… Success!
Winmerge was now running in my Windows 10 laptop!
Note: This as been reported to also happen on Windows 8.1.