Transformation metrics and errors

CloudWatch Logs publishes transformation metrics to CloudWatch. These metrics include TransformedLogEvents, TransformedBytes, and TransformationErrors. For more information, see Log transformer metrics and dimensions.

Whenever CloudWatch Logs tries and fails to transform a log event, it adds a @transformationError system field to that log event. When you run a CloudWatch Logs Insights query, you will see this field in all log events that had a transformation failure. You can query for this field with a query such as filter ispresent(@transformationError) to find all the failed transformation events.