cloudflare/vinext

Pages Router: API route returns 500 when middleware is present

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#1,477 opened on May 22, 2026

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Description

This issue was created by an agent analysing CI failures from the Next.js Deploy Suite (vinext main vs Next.js v16.2.6, 2026-05-22).

Problem

When a Pages Router app defines middleware and a client makes a request to /api/*, the API handler returns Internal Server Error (HTTP 500) instead of executing. The middleware pipeline appears to interfere with API route dispatch.

GET /api/* with middleware returns 500

Estimated Impact

~2 test failures across the deploy suite.

Affected Test Suites

  • test/e2e/proxy-request-with-middleware/test/index.test.ts (2 failures)

Recommendation

  1. Reproduce first in vinext's own test suite. Add a Pages Router fixture with a no-op middleware.ts and pages/api/hello.ts. Assert /api/hello returns 200.

  2. Fix the middleware -> API route handoff. After middleware runs and chooses to fall through (no rewrite/redirect), /api/* routes must dispatch normally instead of crashing.

  3. Related, but not duplicate, of #1338. #1338 covers edge runtime API routes returning 500/404; this is node runtime API routes returning 500 specifically because middleware is configured.

Contributor guide

Research direction
Locate the middleware execution handler in the vinext codebase. When middleware calls 'NextResponse.next()' and returns, ensure that the request dispatches to the correct API route handler without throwing an internal error. Add a test fixture for Pages Router with middleware and an API route to reproduce the 500 error, then trace the request flow to find where the crash occurs.
Tech stack
typescriptnodejsvite
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitNode.js
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65