# Event Streams to Kafka: the file-based config shapes, and five silent failure modes to know about

**URL:** <https://forum.inductiveautomation.com/t/event-streams-to-kafka-the-file-based-config-shapes-and-five-silent-failure-modes-to-know-about/116696>\
**Category:** Ignition\
**Created:** [August 7, 2026, 7:01am UTC](https://forum.inductiveautomation.com/t/event-streams-to-kafka-the-file-based-config-shapes-and-five-silent-failure-modes-to-know-about/116696 "2026-08-07T07:01:33Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Aradh\_Suresh](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/aradh_suresh/32/86613_2.png) [@Aradh\_Suresh](https://forum.inductiveautomation.com/u/Aradh_Suresh)\
**Post date:** [August 7, 2026, 7:01am UTC](https://forum.inductiveautomation.com/t/event-streams-to-kafka-the-file-based-config-shapes-and-five-silent-failure-modes-to-know-about/116696/1 "2026-08-07T07:01:33Z")

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I have been running 8.3.8 Event Streams publishing to a Kafka-compatible cluster (Redpanda), authoring the streams as project files rather than in the Designer, and hit a few things worth sharing since I could not find them documented anywhere.

The Kafka handler's `topic` / `key` / `value` fields are ExpressionValue objects (`{"data": ..., "type": "STATIC" | "EXPRESSION"}`) - a bare string parses without complaint and produces nothing. Tag identity lives in event metadata (`{event.metadata.tagPath}`), not in data. `sourceEncoder`, `batch`, `filter`, `transform` and `onError` are all required, and each missing one is a separate NPE at stream creation. Batch timers set to 0 are disabled, not fast - the stage then flushes only at `maxQueueSize`, which at low tag rates looks exactly like a dead pipe. And a file-based config change needs Scan File System twice: the first scan shuts the stream down, the second one starts the replacement.

The silent one to watch: `failureStrategy: IGNORE` reports the handler GOOD with zero errors while delivering nothing, and a malformed handler entry unregisters the whole stream with no log line at all.

Happy to share the working config.json shapes if useful. Full write-up with the measurements (including a kill battery: broker down, database down, gateway restart, each loss-accounted against a 1 Hz heartbeat tag) is here: [Event Streams to TimescaleDB: the config recipe, five silent failures, and a loss-accounted kill battery — Aradh Suresh](https://aradhs.com/lab/event-streams-to-timescaledb)

Some of this may be specific to Event Streams 1.3.8 - corrections welcome if anyone from IA sees this.