fix(nextjs): improve auth() error message to mention infrastructure failures

[jacekradko]

Summary

• Improved the auth() error message when clerkMiddleware() is not detected to include infrastructure failures as a possible cause
• When middleware is correctly configured but fails to execute due to edge runtime errors or platform outages (e.g. Cloudflare issues), the current error message only suggests configuration problems, which sends developers on a wild goose chase
• The new message adds a hint that infrastructure issues can also cause this error

How it looks

Before:

Clerk: auth() was called but Clerk can't detect usage of clerkMiddleware(). Please ensure the following:
- Your middleware file exists at ./src/middleware.(ts|js)
- clerkMiddleware() is used in your Next.js middleware file.
- Your middleware matcher is configured to match this route or page.
- If you are using the src directory, make sure the middleware file is inside of it.

After:

Clerk: auth() was called but Clerk can't detect usage of clerkMiddleware(). Please ensure the following:
- Your middleware file exists at ./src/middleware.(ts|js)
- clerkMiddleware() is used in your Next.js middleware file.
- Your middleware matcher is configured to match this route or page.
- If you are using the src directory, make sure the middleware file is inside of it.
- If your middleware file and matcher are configured correctly, this error can also occur if the middleware failed to run on this request (e.g. due to an edge runtime error or platform outage).

Test plan

• Verified error message renders correctly with and without prefixSteps
• No logic changes, only string update

Summary by CodeRabbit

• Bug Fixes

  • Clarified authentication error messaging: when auth checks fail, the message now explicitly notes that verified configuration issues can also stem from runtime or infrastructure problems (e.g., platform outages or execution environment errors), helping users distinguish configuration issues from transient service/runtime failures.

• Chores

  • Added a changelog entry recording the improved error message.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Skipped		Mar 9, 2026 7:04pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 0920cf9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@clerk/nextjs	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

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ℹ️ Recent review info

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Run ID: 27cc09f8-63f6-4409-bcdb-3e4212f990f8

📥 Commits

Reviewing files that changed from the base of the PR and between d16df7d and 0920cf9.

📒 Files selected for processing (1)

• packages/nextjs/src/server/errors.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/nextjs/src/server/errors.ts

---

📝 Walkthrough

Walkthrough

Adds a changeset file for a patch release of @clerk/nextjs and updates the authAuthHeaderMissing error message in packages/nextjs/src/server/errors.ts to also indicate that infrastructure or communication issues (e.g., edge runtime errors or platform outages) can cause the error when clerkMiddleware() is not detected. No public API, function signature, or behavioral changes were introduced.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: improving the auth() error message to mention infrastructure failures.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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commit: 0920cf9