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MIDDLEWARE_RUNTIME_DEPRECATED

Last updated October 6, 2025

The error occurs when a middleware is using a deprecated runtime. This error can occur when a middleware is using a runtime that is no longer supported by the platform.

503

MIDDLEWARE_RUNTIME_DEPRECATED:

Middleware Runtime Deprecated

Troubleshoot

I'm encountering an error and reviewing the docs at /flg~eyJhbGciOiJIUzI1NiJ9._v7-_v79_g.IN_1YP9lSd3iAlrWfWlSjd7w2BXkRLu_kcJ1imlrEiA/docs/errors/MIDDLEWARE_RUNTIME_DEPRECATED to understand what's happening. Please help me resolve this by: 1. **Suggest the fix**: Analyze my codebase context and propose what needs to be changed to resolve this error 2. **Explain the root cause**: Break down why this error occurred: - What was the code actually doing vs. what it needed to do? - What conditions triggered this specific error? - What misconception or oversight led to this? 3. **Teach the concept**: Help me understand the underlying principle: - Why does this error exist and what is it protecting me from? - What's the correct mental model for this concept? - How does this fit into the broader framework/language design? 4. **Show warning signs**: Help me recognize this pattern in the future: - What should I look out for that might cause this again? - Are there similar mistakes I might make in related scenarios? - What code smells or patterns indicate this issue? 5. **Discuss alternatives**: Explain if there are different valid approaches and their trade-offs My goal is to fix the immediate issue while building lasting understanding so I can avoid and resolve similar errors independently in the future.

To troubleshoot this error, follow these steps:

  1. Identify the affected project: Use Vercel Logs to identify if your project is experiencing this error. Look for the error in your project's runtime logs.
  2. Locate the middleware: Once you've identified the project, check if it has a or file in the root directory or uses Routing Middleware in any way.
  3. Redeploy the project: Redeploy the project to automatically upgrade to the latest supported runtime version. However, if the redeploy fails, you may need to:
    • Update your Node.js version: Check your project's Node.js version setting in the Vercel dashboard or and update it to a supported version
    • Update dependencies: Outdated dependencies may not be compatible with newer Node.js versions. Update your dependencies to their latest compatible versions before redeploying

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