Structured Output Error | Mistral AI | Page 1

humble flame Jul 30, 2025, 11:47 PM

#

Good evening, the API is having an issue using client.chat.parse with a responseFormat for a structured output.
Yet, a few hours ago, it still worked.
Is anyone else experiencing this issue?

**Code : **


const { z } = require('zod');

const Book = z.object({
  name: z.string(),
  authors: z.array(z.string()),
});

const apiKey = "...";

const client = new Mistral({ apiKey: apiKey });

(async () => {
  const chatResponse = await client.chat.parse({
    model: "ministral-8b-latest",
    messages: [
      {
        role: "system",
        content: "Extract the books information.",
      },
      {
        role: "user",
        content: "I recently read 'To Kill a Mockingbird' by Harper Lee.",
      },
    ],
    responseFormat: Book,
    maxTokens: 256,
    temperature: 0,
  });

  console.log(chatResponse);
})();

**Output : **

SyntaxError: Unexpected token '`', "`\\`\\`json
{
"... is not valid JSON
    at JSON.parse (<anonymous>)
    at convertToParsedChatCompletionResponse (<...>\node_modules\@mistralai\mistralai\extra\structChat.js:34:63)
    at Chat.parse (<...>\node_modules\@mistralai\mistralai\sdk\chat.js:24:91)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async <...>\app.js:305:24

#

Structured Output Error

empty sluice Jul 31, 2025, 3:08 AM

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Yeah, I've had 2 chats on le chat through web interface stick in 'thinking mode' I can expand and see what was going to be the output... but I see a "\boxed{" near the end then a } ....

meager ferry Jul 31, 2025, 7:27 AM

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@green schooner quite urgent, a bug seems to have been released on structured outputs.

curl --location "https://api.mistral.ai/v1/chat/completions" \ --header 'Content-Type: application/json' \ --header 'Accept: application/json' \ --header "Authorization: Bearer $MISTRAL_API_KEY" \ --data '{ "model": "ministral-8b-latest", "messages": [ { "role": "system", "content": "Extract the books information." }, { "role": "user", "content": "I recently read To Kill a Mockingbird by Harper Lee." } ], "response_format": { "type": "json_schema", "json_schema": { "schema": { "properties": { "name": { "title": "Name", "type": "string" }, "authors": { "items": { "type": "string" }, "title": "Authors", "type": "array" } }, "required": ["name", "authors"], "title": "Book", "type": "object", "additionalProperties": false }, "name": "book", "strict": true }'"temperature": 06,

{"id":"41fdc9d06ac74e0081c9ad81d300071b","created":1753946653,"model":"ministral-8b-latest","usage":{"prompt_tokens":21,"total_tokens":123,"completion_tokens":102},"object":"chat.completion","choices":[{"index":0,"finish_reason":"stop","message":{"role":"assistant","tool_calls":null,"content":"```json\n{\n \"properties\": {\n \"name\": {\n \"title\": \"Name\",\n \"type\": \"string\"\n },\n \"authors\": {\n \"items\": {\n \"type\": \"string\"\n },\n \"title\": \"Authors\",\n \"type\": \"array\"\n }\n },\n \"required\": [\"name\", \"authors\"],\n \"title\": \"Book\",\n \"type\": \"object\",\n \"additionalProperties\": false\n}\n```"}}]}

⚠️ The output choices[0].message.content returns the input structured !

meager ferry Jul 31, 2025, 7:49 AM

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The problem seems to occur with ministral-8b only, ministral-3b, large, medium, etc seem to be ok

humble flame Jul 31, 2025, 9:50 AM

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Any news yet ?

meager ferry Jul 31, 2025, 9:53 AM

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I tried contacting the support, but nothing on that side either..

humble flame Jul 31, 2025, 9:54 AM

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but they answered?

humble flame Jul 31, 2025, 10:16 AM

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I receive this from the IT Support :

We apologize for any inconvenience you may have experienced.

We have flagged this issue for further investigation by our engineers and will keep you updated on the outcome!

Thank you for your patience,
Mistral AI - Support Team

meager ferry Jul 31, 2025, 11:46 AM

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I have had no answer on my side, it just says "Ticket has been updated • 3h ago In progress"

#

Thanks for sharing !

green schooner Jul 31, 2025, 11:54 AM

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Update: the team is working on this 👍 will keep u updated

meager ferry Jul 31, 2025, 12:04 PM

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Thank you !

green schooner Jul 31, 2025, 1:52 PM

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@meager ferry and @humble flame should be fixed now, can u confirm?

meager ferry Jul 31, 2025, 1:57 PM

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I confirm, thanks !

slate cargo Jul 31, 2025, 2:53 PM

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green schooner <@1338432134058082364> and <@969632982518349844> should be fixed now, can u conf...

Was this related to image annotation with Image Schema ?
Should OCR works too now ?

humble flame Jul 31, 2025, 10:11 PM

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Yes !! Thanks @green schooner

mossy canyon Aug 1, 2025, 7:03 AM

#

Hi,
I have the similar code,

import { Mistral } from "@mistralai/mistralai";
import { z } from "zod";

const Book = z.object({
  name: z.string(),
  authors: z.array(z.string()),
});

const apiKey = process.env.MISTRAL_API_KEY;

const client = new Mistral({ apiKey: apiKey });

const chatResponse = await client.chat.parse({
  model: "ministral-8b-latest",
  messages: [
    {
      role: "system",
      content: "Extract the books information.",
    },
    {
      role: "user",
      content: "I recently read 'To Kill a Mockingbird' by Harper Lee.",
    },
  ],
  responseFormat: Book,
  maxTokens: 256,
  temperature: 0,
});

when run,

/home/user/temp/mistral/node_modules/.pnpm/@[email protected][email protected]/node_modules/@mistralai/mistralai/src/lib/schemas.ts:49
    return ERR(new SDKValidationError(errorMessage, err, rawValue));
               ^


SDKValidationError: Input validation failed: TypeError: Cannot read properties of undefined (reading '_zod')
    at safeParse (/home/user/temp/mistral/node_modules/.pnpm/@[email protected][email protected]/node_modules/@mistralai/mistralai/src/lib/schemas.ts:49:16)
    ...
    maxTokens: 256,
    temperature: 0,
    responseFormat: {
      type: 'json_schema',
      jsonSchema: {
        name: 'placeholderName',
        schemaDefinition: {
          type: 'string',
          '$schema': 'http://json-schema.org/draft-07/schema#'
        },
        strict: true
      }
    }
  },
  rawMessage: 'Input validation failed'
}

green schooner Aug 1, 2025, 7:24 AM

#

mossy canyon Hi, I have the similar code, ```ts import { Mistral } from "@mistralai/mistralai...

Hi there, could you update your sdk version? mspeed

mossy canyon Aug 1, 2025, 7:27 AM

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I'm running the v1.7.5,

$ pnpm ls
Legend: production dependency, optional only, dev only

[email protected] /home/user/temp/mistral (PRIVATE)

dependencies:
@mistralai/mistralai 1.7.5
dotenv 17.2.1
zod 4.0.14

I still see the same issue after deleting node_modules and re-installed the packages.

green schooner Aug 1, 2025, 7:40 AM

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Thats a bit surprising, will take a quick look

mossy canyon Aug 1, 2025, 7:51 AM

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I suspect it could caused by the Zod. When I downgrade the Zod from v4 to 3.25.76, it throws

SDKError: API error occurred: Status 401 Content-Type application/json; charset=utf-8 Body 
{"detail":"Unauthorized"}
    at matchFunc (/home/user/temp/mistral/node_modules/.pnpm/@[email protected][email protected]/node_modules/@mistralai/mistralai/src/lib/matchers.ts:236:16)

but I can still run OCR API without any problem ...

#Structured Output Error