pdftk not able to open file

Question

I am trying to fill data into a pdf from a xfdf file.

pdftk /templates/pdf/2018/data_file_1.pdf fill_form /tmp/input_xfdf.xfdf output /tmp/output.pdf

But It is showing this error.

Error: Failed to open form data file: 
   /tmp/input_xfdf.xfdf
   No output created.

I have tried this answer also and have given folder access.