Issue
You’re trying to fill a PDF form using PDF.co in Zapier but get this error:
“Fieldname must not be empty.”
Why This Happens
PDF.co requires form data in this format:
pageNumber;fieldName;value
Each part must be separated by a semicolon (;) and none can be left blank.
If the field name is missing or empty, the system can’t process the request—resulting in this error.
How to Fix It
Check that you’re using semicolons to separate the page number, field name, and value.
Make sure the field name is not empty and is placed in the middle of the input.
Follow this format exactly:
Example:
1;FirstName;John
Helpful Tips
Double-check the exact field names in your PDF (use PDF.co’s PDF Form Field Detector if needed).
Avoid using commas or other symbols—Zapier only accepts semicolons as separators.