Assistant API File creation Error: [404] Invalid URL

Hey there,

I am trying to feed my assistant with files via API, I am doing the following steps:

  1. Upload File via API with purpose Assistant : works great, file is in the directory
  2. Creating the file via the assistant API (connect the existing file to the assistant where to use.

But the creation of the file does not work, I always get the error “[404] Invalid URL (GET /https:/”

This is my call:

        "url": "",
        "body": "{\n      \"file_id\": \"file-4LyxtM9hNooaFaxYet18Kg48\"\n    }'",
        "method": "POST",
        "headers": [
                "key": "Content-Type",
                "value": "application/json"
                "key": "OpenAI-Beta",
                "value": "assistants=v1"

Please do not wonder, the authorisation is not in the call i pasted here, but it is also included and works. Just the URL of the file does not want to work.

Do you have any ideas?