If you are trying uploading a logbook data loader, but this is fetching back error messages on the validation step:
Review the background check validation.
If you are sure your template is correct, copy the data into a new spreadsheet, make the relevant changes, and try to upload again.
Make sure to remove the instructional text from the top of the default template.
If this still fails, raise a new case and provide:
A copy of the sheet you are trying to validate.
Access to your system.