Read-only File System Error in Zapier's Python Step for PDF Handling

Other Questions Zapier
1

I encounter a read-only system error in my Zapier Python step when processing a PDF. How can I handle the PDF entirely in memory?

import requests
from io import BytesIO

pdf_response = requests.get(input_data['pdf_url'])
pdf_stream = BytesIO(pdf_response.content)

file_payload = { 'document': pdf_stream.getvalue() }

params = {
    'test_mode': 1,
    'doc_title': 'In-Memory PDF',
    'recipient_email': input_data['email'],
    'recipient_name': input_data['name']
}

endpoint = 'https://api.hellosign.com/v3/signature_request/send'
result = requests.post(endpoint, files=file_payload, data=params)
print(result.status_code)
2

The solution that worked for me was to pass the PDF as a proper file tuple in the requests.post call. I remember encountering a similar situation while testing on Zapier. Instead of writing the PDF bytes to disk, I kept the content in memory by using BytesIO and then constructed a tuple with a filename, the BytesIO object, and the appropriate device type. This approach prevents the read-only file system error and ensures that the API receives the file in a format it expects. Adjusting the file_payload structure made the process significantly smoother.

3

In my experience, ensuring that the PDF is handled entirely in memory involves passing the stream correctly to the API without prematurely converting it to raw bytes. The important aspect is to create and maintain the BytesIO instance directly as part of the file upload, so the multiparty form data is recognized as a file object. Explicitly providing the filename, the stream, and its mime type proved effective in avoiding read-only errors. Confirming the remote API’s expected file structure and adjusting the payload accordingly can resolve such issues reliably.