Apache + mod_wsgi + flask app: "Unable to get bucket brigade for request" error in logs
It usually means that the HTTP client making the request dropped the connection before the request content could all be read. If you are dealing with slow clients on mobile phone networks, it is not uncommon to see this.
As to whether you can handle it so it is ignored and nothing logged, I would need to see the complete context of the error message to see whether it is generated in conjunction with an IOError exception in Python. If it is, the Python code could catch it and deal with and return a 500 error response but not log anything.