Inline attachment of pdf using useChat failing

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1

Azure open ai - gpt-5.4-mini
@ai-sdkai-sdk/react - 2.0.187
@ai-sdk/azure - 2.0.17
ai - 5.0.121
When sending file attachments more than 50 mb throwing failed to download file. File urls can not be larger than 32 mb. I am sending pdf as url below 32 like 30mb files working fine. Could you please help? Any docs to see how many file can be support

2

Hi,

The important part of the error is:

File URLs can not be larger than 32 MB

So the request is likely being rejected by the file URL / attachment path before the model can process the PDF.

Since ~30 MB files work and larger files fail, I would treat 32 MB as the practical limit for this URL-based attachment flow unless the AI SDK/Azure provider team confirms otherwise.

For larger PDFs, I would avoid sending the entire file inline through useChat. A more reliable pattern is:

  1. Upload the PDF separately.

  2. Parse or extract the PDF text server-side.

  3. Split the text into chunks.

  4. Send only the relevant chunks to the model.

  5. For larger documents, use a RAG/vector-search flow instead of attaching the whole PDF to each chat request.

It would also be useful if someone from the AI SDK/Vercel team could confirm whether the 32 MB limit comes from useChat, the AI SDK attachment handling, Azure OpenAI, or the file-fetching layer.