AFAIK some recent commits patches (e,g [1] for the "slot sync" development) have created some more cases of "could not connect..." messages. So, you might need to enhance your patch to deal with any new ones in the latest HEAD.
====== [1] https://github.com/postgres/postgres/commit/776621a5e4796fa214b6b29a7ca134f6c138572a Kind Regards, Peter Smith. Fujitsu Australia
