If your Deepgram SDK throws ValidationError about unknown Listen V2 message types like ConfigureSuccess, you are on an SDK version that predates the backend's message types. Upgrade to deepgram-sdk 6.0.1 or later on v6, or 5.3.3 on v5, which added the missing types. Do not stay on 6.0.0 with Listen V2 / Flux.

Context: Deepgram python SDK issue #668 (closed, maintainer fixed): upgrading to SDK v6 (or running v5 with Listen V2 / Flux) crashed with pydantic ValidationError: 'ListenV2FatalError.description Field required' and 'ConfigureSucces...' types unknown to the SDK. The root cause was the V2 backend sending message types like ConfigureSuccess that the SDK's strict response validation did not recognize. Deepgram maintainer lukeocodes acknowledged the bug and released patches on both channels: 6.0.1 and 5.3.3. A community workaround was to patch the response union types manually until upgrading.