OpenTelemetry .NET Instrumentation v1.19.0: Kafka Span Fix and Runtime Async Support

OpenTelemetry .NET Instrumentation v1.19.0 shipped on November 4, 2026. The two changes most likely to matter in production are a fix for unfinished Kafka ProduceAsync spans and new instrumentation support for methods compiled with the experimental .NET runtime async feature.

The full release notes and downloads are on the GitHub release page.

Kafka spans and YAML configuration fixes

Kafka producers previously left spans unfinished when no delivery result was available. The release also patches instrumentation errors in the same path. If you autoinstrument Kafka producers, this one is worth picking up.

File-based YAML configuration got stricter and more forgiving at the same time:

  • Sequences and mappings supplied for scalar fields are now rejected instead of silently misbehaving.
  • Trace ID sampling ratios get scalar validation, default to 1.0 when the ratio is omitted or null, and reject invalid values.
  • Empty environment variables fall back to configured values, and undefined variables without a fallback resolve to an empty value.

OpAMP reporting changed too. Full state reports requested by the server are coalesced, and consecutive sends are spaced by at least five seconds. That reduces chatter between the plugin and the OpAMP server.

Runtime async support and dependency updates

Autoinstrumentation now covers code compiled with the experimental .NET runtime async feature. If you are testing that runtime mode, the profiler can trace those methods. The maintainers are not claiming runtime async is generally recommended yet.

Dependency bumps:

  • OpenTelemetry.OpAmp.Client moved from 0.9.0-alpha.1 to 0.9.0-alpha.3.
  • .NET Framework only: OpenTelemetry.Instrumentation.AspNet and OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule both moved from 1.20.1 to 1.20.2.

Upgrade notes

Nothing marked as breaking in this release. One note for .NET Framework users: the release also prevents assembly redirection from hanging or reusing stale references when assembly reference enumeration fails. If you have seen odd startup behavior under the profiler, try this version.

Where to get it

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