What causes the "Failed to index document" error in Tracardi, and how can it be solved?

The "Failed to index document" error occurs when there is a conflict in the schema between the data being sent to Tracardi and the existing data in Tracardi. This conflict arises when the data type being sent conflicts with the existing data type. To resolve this error, ensure that the data being sent matches the expected data type defined in the Tracardi schema.