Part exceeded maximum size of 1024KB

[dan-jensen]

Problem

When trying to upload a JPG file I'm encountering invalid_request_error: "Part exceeded maximum size of 1024KB."

It looks like this gem is setting the media-type to "multipart/form-data" as expected, but then submitting file as a string parameter instead of a file upload. UPDATE: The problem was this gem was setting an invalid Content-Disposition part header so servers were parsing the file param as a string instead of a file upload.

Details

• Claude API documentation says "Maximum file size: 500 MB per file".
• My file is 1.1MB
• A web search indicates this error message "Part exceeded maximum size of 1024KB" originates from Starlette, so I assume the Claude API uses Starlette.
• Can replicate with both String and StringIO values for file.
• Can replicate this error across multiple environments (development and production).
• Can replicate with and without shorter multipart boundaries.
• Cannot replicate with cURL, meaning the problem seems to be with how this gem is sending requests.
• This is NOT a problem with extra headers like betas: "anthropic-beta" or params like beta=true.

Code

anthropic = Anthropic::Client.new
file_string = File.read('/some/path/file.jpg')
anthropic.beta.files.upload(file: file_string)

Anthropic::Errors::BadRequestError
{
  :url=>"https://api.anthropic.com/v1/files?beta=true",
  :status=>400, 
  :body=>{
    :type=>"error", 
    :error=>{
      :type=>"invalid_request_error", 
      :message=>"Part exceeded maximum size of 1024KB."
    }, 
    :request_id=>"req_011CSoyEPUAzWgTzPoJfESpt"
  }
}

[dan-jensen]

Found the problem. Both Starlette (Anthropic) and Rack require the Content-Disposition to include filename, but this gem does not enforce that requirement. (This gem uses custom multipart logic instead of multipart-post, which is the closest thing to a Ruby convention for multipart.)

What the line looks like now:

Content-Disposition: form-data; name="file"

What it needs to look like:

Content-Disposition: form-data; name="file"; filename="local.path"

Pushed a PR with the fix: #126

[ms-jpq]

Please see:

#126 (comment)

---

hi @dan-jensen,

you are absolutely right in that we should do a better job making sure the file uploading API harder to mis-use.

Currently this is documented under https://github.com/anthropics/anthropic-sdk-ruby?tab=readme-ov-file#file-uploads. But it is not clear that some APIs ought to take in a name.

I do hesitate to merge in this PR as it is, since we would be baking in a default behaviour that is different from the other SDKs. I will go and convene with my colleagues to ensure a consistent default behaviour across SDKs first 👍 .

Thank you so much for taking note of this!

---

I will follow up as soon as that is done 👍 , thank you for the patience.