fail to bundle install puma 4.3.5 or gem puma with ruby-2.6.6 on macos-10.15.6

fail to bundle install puma 4.3.5 or gem puma with ruby-2.6.6 on macos-10.15.6 try to bundle dependencies for my project, but puma 4.3.5 occured an error. someone know about this? xxxxxxxxxxxx here...