For my project problem was related to pod Cache which gives error when Optimization Level for Release is set to Optimize for Speed [-O]. I have set Compilation Mode to Whole Module again and set optimization level for the pod in pod file:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    # Cache pod does not accept optimization level '-O', causing Bus 10 error. Use '-Osize' or '-Onone'
    if target.name == 'Cache'
      target.build_configurations.each do |config|
        level = '-Osize'
        config.build_settings['SWIFT_OPTIMIZATION_LEVEL'] = level
        puts "Set #{target.name} #{config.name} to Optimization Level #{level}"
      end
    end
  end
end

Refrence: https://github.com/hyperoslo/Cache/issues/233#issuecomment-477749560

I fixed this issue by going Pods Project then to the building settings and setting Compilation Mode to Incremental for Release. Then clean and archive, should compile fine then.

So I had same issue when updating my project to Swift 5. For some reason, Cocoapods (latest version, 1.6.1) set the SWIFT_VERSION of some pods to Swift 5 even if they're released as Swift 4, 4.1, 4.2 pods. So I had to add a post install script that set the correction version of swift like so

post_install do |installer|
  installer.pods_project.targets.each do |target|
    if target.name == 'CryptoSwift' || target.name == 'SwiftyBeaver'
      target.build_configurations.each do |config|
        config.build_settings['SWIFT_VERSION'] = '4.2'
      end
    end
  end
end