Manifest may not be valid or the file could not be opened.

Question

I know it is a very commonly faced problem. But, there is a slight difference, my WPF installs perfectly and runs on Windows 7 and Windows 8 OSes. But, when tried to install

Answer 1

It's because your developer machine had .NET 4.5 installed, while your client machines only had .NET 4.0 installed. The .NET 4.0 client machines can't read the manifest, as they expect SHA-1, while the .NET 4.5 developer machines can.

Answer 2

I was able to solve my issue by removing the signing of the manifest.
If you right-click your project and go to properties then to the Signing Tab; uncheck the Sign the ClickOnce manifests and Sign the assembly.
I'm not sure what this does in terms of security but my app installed after I removed these options.