问题 It seems uwsgi remembers headers from a previous request in async mode! I deployed a very simple application with uwsgi: def application(environ, start_response): start_response('200 OK', [('Content-Type', 'text/plain')]) environ_repr = '\n'.join(sorted(key.ljust(30) + ' = ' + repr(value) for key, value in environ.items())) return [environ_repr] and ran it with: uwsgi --module index -s 0.0.0.0:8000 -p 1 --async 5 Steps to regenerate the problem: Visit 127.0.0.1:8000 with header "Key: Value",