Hey , I am not being able to create a linkedin post with multiple images , getting a 400 error

[Pratham]

Help Needed: LinkedIn Carousel Post with Multiple Images via Make.com

Hi everyone,

I’m building a scenario in Make.com to post multi-image (carousel-style) posts to LinkedIn using their /rest/posts API.

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What I’m trying to do:

• Collect Google Drive links (screenshots) submitted via a form.
• Extract the file IDs, convert them to direct download URLs, and fetch each image using HTTP > Get a file.
• Upload each image to LinkedIn using initializeUpload and a PUT request to the returned uploadUrl.
• Store all asset URNs (like urn:li:image:xxx) and publish a single post with all the images together (as a media group or carousel).

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Tools used:

• Text Parser (regex) to extract Google Drive file IDs.
• Iterator to loop through each ID and download the file.
• HTTP - Make a Request (PUT) to upload each image.
• Text Aggregator / Array Aggregator to collect asset URNs.
• LinkedIn Post API using HTTP - Make a Request to /rest/posts.

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The problem:

No matter how I aggregate the uploaded image URNs, I’m unable to send a proper media array to LinkedIn. The post either fails with:

400: Request body could not be converted to data map

Or it silently fails with an empty/unavailable post.

Even after using:

• Text Aggregator → Parse JSON (tried both)
• Making sure my final JSON body looks like:

"media": [
  {
    "status": "READY",
    "media": "urn:li:image:D4E10AQEXAMPLE1"
  },
  {
    "status": "READY",
    "media": "urn:li:image:D4E10AQEXAMPLE2"
  }
]

…it either gets stringified, breaks the JSON format, or results in separate post attempts.

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What I’ve tried:

• Text Aggregator with and without Group By
• Array Aggregator → still results in multiple bundles or stringified text
• Parse JSON to parse the final array back → still doesn’t map as expected
• Tried placing the aggregated object in raw HTTP body

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What I’m looking for:

• A step-by-step module config on how to:
  1. Upload multiple images to LinkedIn
  2. Collect the asset URNs correctly
  3. Format and post them in a single carousel-style post
• Preferably using only native Make.com modules (within the free tier)

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Additional Context:

• I’m using LinkedIn Personal Profile (not Company Page)
• I have working initializeUpload and PUT upload logic
• I already successfully posted single image and text-only posts

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If someone has done this before or can point to a working example (or even a blueprint), I’d be super grateful!

Thanks in advance for your time!

– Pratham