# Error: headers() must be accessed before any other request processing in middleware

- **ID:** `nextjs/headers-must-be-accessed-before-any-other-request-processing`
- **Domain:** nextjs
- **Category:** runtime_error
- **Verification:** ai_generated
- **Fix Rate:** 78%

## Root Cause

In Next.js middleware, the headers() function is called after other request processing, causing a race condition where the request context is no longer available.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| next@14.2.0 | active | — | — |
| next@14.2.5 | active | — | — |
| next@15.0.0-rc.1 | active | — | — |

## Workarounds

1. **Call headers() at the very beginning of the middleware function before any other async operations or conditionals.** (85% success)
   ```
   Call headers() at the very beginning of the middleware function before any other async operations or conditionals.
   ```
2. **If using multiple middleware functions, ensure headers() is only called in the first middleware and pass the result via request headers or locals.** (75% success)
   ```
   If using multiple middleware functions, ensure headers() is only called in the first middleware and pass the result via request headers or locals.
   ```
3. **Upgrade to Next.js 15 where the middleware API has been updated to handle headers() more robustly.** (90% success)
   ```
   Upgrade to Next.js 15 where the middleware API has been updated to handle headers() more robustly.
   ```

## Dead Ends

- **** — This does not fix the root cause; the error still occurs but is silenced, leading to undefined headers. (70% fail)
- **** — headers() must be synchronous and called immediately; async wrappers lose the request context. (85% fail)
- **** — This is a syntax error, not a timing issue; it doesn't address the race condition. (90% fail)