On a QUIC or HTTP/2 connection, if a request receives a 408 response, the request can be retried an infinite number of times.

Chrome retries 408 if the connection was reused [1]. I believe this logic was added for HTTP/1.1 connections where there is a concern that the server might close Keep-Alive connections prematurely. Chrome wants to retry in case the request will succeed on a fresh connection. However, IsConnectionReused() is basically always true for QUIC [2] and HTTP/2 [3] connections. This results in infinite retry for QUIC and HTTP/2 when the response code is deterministically 408. I suspect there may be a similar bug here [4] although I'm not too familiar with that code.

Contact me privately for a repro.

[1] https://cs.chromium.org/chromium/src/net/http/http_network_transaction.cc?rcl=aa1f961e37c8778191049bca02608cc54f389366&l=1249
[2] https://cs.chromium.org/chromium/src/net/quic/chromium/quic_http_stream.cc?rcl=caca06866f37c79df89cab9a634bb7497177236e&l=373
[3] https://cs.chromium.org/chromium/src/net/spdy/spdy_session.cc?rcl=caca06866f37c79df89cab9a634bb7497177236e&l=1297
[4] https://cs.chromium.org/chromium/src/net/http/http_network_transaction.cc?rcl=258758c687d31cc18e1f9f0395a8714df0187202&l=1599