GitHub user hachikuji opened a pull request: https://github.com/apache/kafka/pull/4280
KAFKA-6289: NetworkClient should not expose failed internal ApiVersions requests The NetworkClient internally ApiVersion requests to each broker following connection establishment. If this request happens to fail (perhaps due to an incompatible broker), the NetworkClient includes the response in the result of poll(). Applications will generally not be expecting this response which may lead to failed assertions (or in the case of AdminClient, an obscure log message). I've added test cases which await the ApiVersion request sent by NetworkClient to be in-flight, and then disconnect the connection and verify that the response is not included from poll(). ### Committer Checklist (excluded from commit message) - [ ] Verify design and implementation - [ ] Verify test coverage and CI build status - [ ] Verify documentation (including upgrade notes) You can merge this pull request into a Git repository by running: $ git pull https://github.com/hachikuji/kafka KAFKA-6289 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/kafka/pull/4280.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #4280 ---- commit 3c7420b2ab51f8d918037681ed9862f0d2676ba7 Author: Jason Gustafson <ja...@confluent.io> Date: 2017-12-01T05:03:54Z KAFKA-6289: NetworkClient should not expose failed internal ApiVersion requests ---- ---