Unrecoverable build error - whilst trying to build setup on VS2015

Question

My build fails every time when I try and build my setup project. The error in the output window is just:

ERROR: Unrecoverable build error

What I have tried already

• Restarting my computer and Visual Studio
• Registering ole32.dll
• Clean and rebuild all
• Deleting bin and obj folders
• Removing temporary files with VS in the name in \AppData\LocalTemp
• Running Visual Studio as an administrator
• Pausing the real time protection on my antivirus
• Deleting the temporary file that the setup build leaves in there.
• Running the process monitor during the build.
• Checking if my project contains duplicate folder names (it does not).

Note: Similar question but not the same as it is for a much earlier version of Visual Studio:

• "Unrecoverable build error" on any MSI Setup project
• “Could not create the file”, “Access is denied” and “Unrecoverable build error” in building setup project in VS 2008

Answer 1

The problem was solved by registering mergemod.dll.

On my computer it is located at: C:\Program Files (x86)\Common Files\Microsoft Shared\MSI Tools

You need to run regsvr32 with administrative privileges to get it to work.

Answer 2

I had to do one additional step on top of the accepted answer:

1. Register the DLL mergemod.dll (regsvr32.exe C:\Program Files (x86)\Common Files\Microsoft Shared\MSI Tools\mergemod.dll)
2. Register the DLL ole32.dll (regsvr32.exe ole32.dll)
3. Delete the cache/temporary visual studio files – which get generated as part of the builds. (C:\users{BUILD_USER}\appdata\local\temp).

Hope that helps!