I updated XCode on my Mac and since then when starting Docker using docker-sync-stack start I get this error message:
docker-sync-stack start
mkmf.rb can\'t find header
None of the other solutions worked for me, here's what I ran to resolve the issue on Mac OS 10.14.x:
sudo rm -rf /Library/Developer/CommandLineTools xcode-select --install sudo xcodebuild -license accept open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg