Release date 2026/08/24
Bugfix
Fixed a permanent failure that started when a broker answered an
ApiVersionsrequest with an error code, an empty API key set, or a malformed frame. The client cached that result and every later request failed withProduceRequest API version not negotiated; broker may be unreachableuntil the node restarted, even after the broker recovered. The client now refuses an unusableApiVersionsresponse, keeps the previous negotiation, and retries the negotiation for a topic whose metadata is already cached.Fixed the confluent schema registry client caching fetched schemas and subjects under keys that did not account for the registry URL or authentication. Instances configured with different credentials could be served each other’s cached lookups, letting an unauthorized instance bypass schema-registry authentication once any authorized instance had warmed the cache. Cache entries are now scoped to the registry identity, and the configured
schema_registry.confluent.ttlis now applied to these cache entries.Fixed a crash that occurred when a plugin set
schema_registry.confluent.authentication.modetooauth2but omitted theoauth2_clientrecord. Previously this returned a 500 from the Admin API during validation, and once saved it also crashed at runtime while fetching the schema registry OAuth2 token. The absentoauth2_clientis now handled and falls back to the default authentication method, so a configuration withoutoauth2_clientworks end-to-end.Fixed an issue where OAuth2 authentication against Confluent Cloud Schema Registry failed because the client did not send the required
target-sr-clusterheader.