In the latest C++ Client 3.4.0 release, we observed a regression https://github.com/apache/pulsar-client-cpp/issues/346. It's a critical bug that a crash could happen for each reconnection.
I pushed a fix (https://github.com/apache/pulsar-client-cpp/pull/347). After it's merged, I will start the release process for 3.4.1. Please let me know if you have any questions. Thanks, Yunze