Skip to main content

Get Support
Have a question? Let's get you an answer!

How Do I...? Troubleshooting Code & Webhooks Developer Zone

Other Help Resources
Wait, there's more! Check out these Community sourced spaces for additional resources.

Zapier Help Center Hire an Expert

Learning Resources
All of our best learning resources can be found here.

Featured Articles Show & Tell Zapier's products AI Hub Zapier Tools Hub

Share your knowledge
Give back to the Community by sharing your automation wins and helping to answer questions.

Share your success See unanswered questions User Groups

Other Learning Resources
Some of our favorite additional ways to upskill your Zapier knowledge.

Zapier Learn Zapier Blog Zapier Webinars

Product Updates
Check out what is new and upcoming with Zapier with our regular product updates.

Product Updates

Early Access Program
Want to join Early Access? Learn more here.

Question

Sending files from Slack to ChatGPT

  • February 26, 2026
  • 0 replies
  • 10 views
B

Hi everyone,

I’m building a workflow to analyze creative briefings (PDF/Docx) using a ChatGPT Assistant (File Search), but I’m stuck on a file-transfer issue between Slack and OpenAI.

Goal: Automatically send files from a Slack message to an OpenAI Assistant for deep analysis.

The Setup:

  1. Trigger: Slack (New Message Posted to Channel).

  2. Action: OpenAI "Upload File" using the Url Private Download from Slack.

  3. Delay: 1 minute for indexing.

  4. Action: "Conversation with Assistant" (File Search enabled).

The Problem: The Assistant gives very generic "hallucinated" output. When I check the Data Out of the "Upload File" step, it shows the file size is only 63,654 bytes. However, the actual file in Slack is 18,810,724 bytes (18.8MB).

It seems OpenAI is only "downloading" a Slack 403 error page or a login redirect instead of the actual binary PDF content.

What I’ve tried:

  • Using Url Private Download instead of Permalink.

  • Both ChatGPT Assistant and regular Conversation give error regarding the files.

  • Clearing Conversation ID to ensure a fresh session.

  • Ensuring File Search is ON in the OpenAI Dashboard.

Question: How do I force Zapier to pass the actual binary File Object (stream) to OpenAI instead of just the URL string, so the Assistant receives all 18.8MB of data?

Any tips would be greatly appreciated!

Terms & ConditionsAccessibility statement