Initial PostScript Template Error for REST Object "UNABLE_TO_LOAD_DOCUMENT"

When I make a simple call to the DocuSign REST ( Post Template ) API , I get the following error:

{
    "errorCode": "UNABLE_TO_LOAD_DOCUMENT",
    "message": "Unable to load the document. Unable to load Document(1: document.pdf). Document is password protected, please remove password protection before using the document."
}

      

        
        
        
      

    

But the document is not password protected. How can I solve this problem?