Thanks for getting in touch! You’ve helped us find a compatibility problem with octo.exe3.4.0 and Octopus Servers older than 3.4.x.
We’ve patched octo.exe to 3.4.1 and tested compatibility between a variety of server versions.
In Octopus 3.4 we now use HTTP POST to perform the Channel Version Rule tests so we can handle SemVer 2 version ranges. The problem was that octo.exe wasn’t falling back to use HTTP GET on older Octopus servers.