Vercel Deploy MIDDLEWARE_INVOCATION_FAILED — Missing @swc/helpers Module

What this error means

MIDDLEWARE_INVOCATION_FAILED: Cannot find module @swc/helpers/esm/_interop_require_default.js is a Next.js failure pattern reported for developers trying to fix vercel deployment failure middleware_invocation_failed missing @swc/helpers. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Minimal reproduction: next@16.2.6 + proxy.ts + top-level @sentry/nextjs import causes MIDDLEWARE_INVOCATION_FAILED on Vercel. @swc/helpers/esm/_interop_require_default.js not included in build.

Common causes

• Next.js 16.2.6 deployments on Vercel fail with MIDDLEWARE_INVOCATION_FAILED when using @sentry/nextjs with proxy.ts, caused by missing @swc/helpers module in the build output
• Minimal reproduction: next@16.2.6 + proxy.ts + top-level @sentry/nextjs import causes MIDDLEWARE_INVOCATION_FAILED on Vercel. @swc/helpers/esm/_interop_require_default.js not included in build.

Quick fixes

1. Confirm the exact error signature matches MIDDLEWARE_INVOCATION_FAILED: Cannot find module @swc/helpers/esm/_interop_require_default.js.
2. Check the Next.js account, local tool state, and provider configuration involved in the failing workflow.
3. Check the build output, project root, and deployment platform configuration before redeploying.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/vercel/next.js/issues/93852

Evidence note: Minimal reproduction: next@16.2.6 + proxy.ts + top-level @sentry/nextjs import causes MIDDLEWARE_INVOCATION_FAILED on Vercel. @swc/helpers/esm/_interop_require_default.js not included in build.

Related errors

• Vercel build command failed
• Next.js middleware error
• Vercel module not found

FAQ

What should I check first?

Start with the exact MIDDLEWARE_INVOCATION_FAILED: Cannot find module @swc/helpers/esm/_interop_require_default.js text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Next.js workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without MIDDLEWARE_INVOCATION_FAILED: Cannot find module @swc/helpers/esm/_interop_require_default.js.