- Security fixes for HTTP/2 -- CVE-2019-9512 (Ping Flood), CVE-2019-9514 (Reset Flood), and CVE-2019-9515 (Settings Flood). Thanks to Jonathan Looney and Piotr Sikora.
- HTTP/2 fixes regarding timeouts.
- trial's assertResultOf, failureResultOf, and successResultOf, now accept Deferred-awaiting coroutines.
- Various other bug fixes for POP3, conch.ssh.keys, and twisted.web.client.FileBodyProducer.
Many thanks to everyone who had a part in this release - the supporters of the Twisted Software Foundation, the developers who contributed code as well as documentation, and all the people building great things with Twisted!