When a file is uploaded, it is first validated following these steps:

1. [Only applies to ZIP uploads] It is checked whether the uploaded ZIP container contains the expected file as specified in the file path setting.
2. It is checked whether the uploaded file is in the expected file format.
3. It is checked whether the identified file contains all expected fields.

If any of these validation steps fail, no data is extracted and an exception message explaining what went wrong will be shown to the participant.