Mync requires Microsoft .NET Framework 4.5 in Windows 7 environment. If it has not been installed, Mync installer will download then install it automamtically. But if connecting to internet fails, this error may appear. Troubleshoot and confirm that internet connection is established then run the Mync installer again.

You may be able to solve the issue by installing Microsoft .NET Framework 4.5.1 offline installer before running the Mync installer.