Invalid File Format – SignatureAPI Docs

What Happened

The provided file format is not supported. SignatureAPI accepts PDF and DOCX files only.

The response includes a detail property with more information about this error.

Convert the file to PDF or DOCX format before uploading.
If the file is already in a supported format, verify the file extension and Content-Type header are correct.
Common unsupported formats include images (PNG, JPG), spreadsheets (XLSX), and plain text (TXT). Convert these to PDF before uploading.