mistral-common-errors

name	mistral-common-errors
description	Diagnose and fix Mistral AI common errors and exceptions. Use when encountering Mistral errors, debugging failed requests, or troubleshooting integration issues. Trigger with phrases like "mistral error", "fix mistral", "mistral not working", "debug mistral".
allowed-tools	Read, Grep, Bash(curl:*)
version	1.12.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","mistral","debugging"]
compatibility	Designed for Claude Code

Mistral AI Common Errors

Overview

Quick reference for diagnosing and fixing Mistral AI API errors. Covers HTTP status codes, SDK-specific issues, streaming failures, and tool calling problems with real solutions.

Prerequisites

• Mistral AI SDK installed
• MISTRAL_API_KEY configured
• Access to application logs

Instructions

Step 1: Quick Diagnostic

set -euo pipefail
# Test API connectivity and auth
curl -s -w "\nHTTP Status: %{http_code}\n" \
  -H "Authorization: Bearer ${MISTRAL_API_KEY}" \
  https://api.mistral.ai/v1/models | jq '.data[].id' 2>/dev/null || echo "FAILED"

# Check env
echo "Key set: ${MISTRAL_API_KEY:+yes}"
echo "Key length: ${#MISTRAL_API_KEY}"

Step 2: Error Reference

---

401 Unauthorized

Error: Authentication failed. Invalid API key.

Causes: Key missing, expired, revoked, or wrong workspace.

Fix:

const apiKey = process.env.MISTRAL_API_KEY;
if (!apiKey) throw new Error('MISTRAL_API_KEY is not set');

// Test the key
const client = new Mistral({ apiKey });
try {
  await client.models.list();
} catch (e: any) {
  if (e.status === 401) {
    console.error('API key invalid — regenerate at console.mistral.ai');
  }
}

Verify manually:

set -euo pipefail
curl -H "Authorization: Bearer ${MISTRAL_API_KEY}" https://api.mistral.ai/v1/models

---

429 Too Many Requests

Error: Rate limit exceeded. Retry-After: 60

Causes: Exceeded RPM (requests/min) or TPM (tokens/min) for your tier.

Fix:

async function withBackoff<T>(fn: () => Promise<T>, maxRetries = 5): Promise<T> {
  for (let i = 0; i <= maxRetries; i++) {
    try {
      return await fn();
    } catch (error: any) {
      if (error.status !== 429 || i === maxRetries) throw error;
      const wait = Math.min(2 ** i * 1000, 60_000);
      console.warn(`Rate limited, retrying in ${wait}ms...`);
      await new Promise(r => setTimeout(r, wait));
    }
  }
  throw new Error('Max retries exceeded');
}

Check your limits: Visit console.mistral.ai/limits for workspace RPM/TPM caps.

---

400 Bad Request — Invalid Model

{"message": "Unknown model: mistral-ultra"}

Fix: Use valid model IDs:

const VALID_MODELS = [
  'mistral-large-latest',
  'mistral-small-latest',
  'codestral-latest',
  'pixtral-large-latest',
  'mistral-embed',
  'mistral-moderation-latest',
] as const;

List available models dynamically:

set -euo pipefail
curl -H "Authorization: Bearer ${MISTRAL_API_KEY}" \
  https://api.mistral.ai/v1/models | jq -r '.data[].id' | sort

---

400 Bad Request — Invalid Messages

{"message": "messages must be a non-empty array"}

Fix: Validate message structure before sending:

function validateMessages(messages: any[]): void {
  if (!messages?.length) throw new Error('Messages array empty');
  const validRoles = ['system', 'user', 'assistant', 'tool'];
  for (const msg of messages) {
    if (!validRoles.includes(msg.role)) {
      throw new Error(`Invalid role: "${msg.role}"`);
    }
    if (!msg.content && !msg.toolCalls) {
      throw new Error(`Message with role "${msg.role}" has no content`);
    }
  }
}

---

400 Bad Request — Tool Call Errors

{"message": "tool_call_id is required for tool messages"}

Fix: Every tool result must include the matching toolCallId:

// After receiving tool_calls from the model
for (const call of response.choices[0].message.toolCalls) {
  const result = await executeFunction(call.function.name, call.function.arguments);
  messages.push({
    role: 'tool',
    name: call.function.name,
    content: JSON.stringify(result),
    toolCallId: call.id,  // REQUIRED — must match call.id
  });
}

---

413 / Context Length Exceeded

Error: Maximum context length exceeded

Fix: Trim conversation history, keeping system message:

function trimToFit(messages: any[], maxChars = 100_000): any[] {
  const system = messages.find(m => m.role === 'system');
  const rest = messages.filter(m => m.role !== 'system');
  const kept: any[] = system ? [system] : [];
  let chars = system?.content?.length ?? 0;

  // Keep most recent messages that fit
  for (let i = rest.length - 1; i >= 0; i--) {
    const msgChars = JSON.stringify(rest[i]).length;
    if (chars + msgChars > maxChars) break;
    chars += msgChars;
    kept.splice(system ? 1 : 0, 0, rest[i]);
  }
  return kept;
}

---

500/503 Server Error

Error: Internal server error

Causes: Mistral service issue (temporary).

Fix:

class CircuitBreaker {
  private failures = 0;
  private lastFailure = 0;
  private readonly threshold = 5;
  private readonly resetMs = 60_000;

  async call<T>(fn: () => Promise<T>): Promise<T> {
    if (this.failures >= this.threshold) {
      if (Date.now() - this.lastFailure < this.resetMs) {
        throw new Error('Circuit breaker open — Mistral service unavailable');
      }
      this.failures = 0; // Reset after timeout
    }
    try {
      const result = await fn();
      this.failures = 0;
      return result;
    } catch (error: any) {
      if (error.status >= 500) {
        .++;
        . = .();
      }
       error;
    }
  }
}

---

ERR_REQUIRE_ESM (Node.js)

Error [ERR_REQUIRE_ESM]: require() of ES Module not supported

Cause: @mistralai/mistralai is ESM-only since v1.x.

Fix: Either use import syntax (recommended) or dynamic import:

// Option 1: Convert to ESM
// package.json: "type": "module"
import { Mistral } from '@mistralai/mistralai';

// Option 2: Dynamic import in CJS
const { Mistral } = await import('@mistralai/mistralai');

---

Network Timeout

Error: Request timeout after 30000ms

Fix:

const client = new Mistral({
  apiKey: process.env.MISTRAL_API_KEY,
  timeoutMs: 60_000, // Increase for long completions
});

// For streaming, the timeout applies to initial connection
// Individual chunks have no timeout

Escalation Path

1. Collect evidence with mistral-debug-bundle
2. Check status.mistral.ai
3. Contact support via Discord or console.mistral.ai

Error Handling

Error	Cause	Solution
401	Auth failure	Regenerate key at console.mistral.ai
429	Rate limit	Backoff + check tier limits
400	Bad params	Validate model, messages, tools
413	Context overflow	Trim conversation history
5xx	Service error	Retry with circuit breaker
ERR_REQUIRE_ESM	CJS import	Use ESM import syntax

Resources

• Mistral API Reference
• Rate Limits & Tiers
• Status Page
• Discord Community

Next Steps

For comprehensive debugging, see mistral-debug-bundle.