Xcode 9 - failed to emit precompiled header [duplicate]

I found out that I accidentally opened the ProjectName.xcodeproj file rather than the ProjectName.xcworkspace file.

Open the xcworkspace file, project will start working again!

Read this if you using cocoapods in project. I just update deployment target to iOS 10 or 11 in my case after updating pods and xcode make first build success. So problem was inside podfile where I had line

platform :ios, '11.0'

and my deployment target in project was 9.0 after I change my podfile to platform to

platform :ios, '9.0'

project was fixed.

Also make sure your import of "ProductModuleName-Swift.h" is in your .m file, and not your .h file.