Microsoft Fabric Error:
IncorrectDataFormat

What does this error mean?

Fabric Activator cannot process data from an eventstream because the events are not in the expected JSON dictionary format. Activator requires each event to be a JSON object with key-value pairs — other formats (arrays, plain text, binary) are rejected.

Common causes

• 1The upstream event source is sending events as a JSON array instead of a JSON dictionary (object)
• 2Event data is serialized as plain text, CSV, or binary (Avro/Protobuf) instead of JSON
• 3The eventstream transformation does not convert the raw event payload to a JSON dictionary before forwarding to Activator
• 4A schema change in the upstream system altered the event format after the Activator connection was configured

How to fix it

1. 1Review the data format in your eventstream: go to eventstream item and inspect the sample event payload.
2. 2Ensure each event is a flat JSON dictionary (e.g., {"temperature": 23, "device": "sensor-1"}) — not a JSON array or nested object at the root level.
3. 3Add a transformation step in the eventstream to convert the payload to the required format before sending to Activator.
4. 4Refer to the Fabric documentation 'Get data from eventstreams' for the exact required JSON format.

Frequently asked questions

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