Vercel deploy MIDDLEWARE_INVOCATION_FAILED + Cannot find module @swc/helpers — Next.js 16.2.x + proxy.ts middleware regression

What this error means

MIDDLEWARE_INVOCATION_FAILED: Cannot find module '/var/task/node_modules/@swc/helpers/esm/_interop_require_default.js' — next@16.2.x + proxy.ts + @sentry/nextjs is a Vercel failure pattern reported for developers trying to fix http 500 middleware_invocation_failed on vercel production deployment caused by @swc/helpers module resolution failure when using next.js 16.2.x app router with proxy.ts middleware convention and sentry installed. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub vercel/next.js issues #93852 (#93850) reported May 2026 with minimal repro. Local build succeeds but Vercel deploy fails with HTTP 500. Blocking production deployments for teams using Next.js 16.2.x + sentry. Not in covered-errors (only generic ‘Vercel build failed’ exists, this is a specific deployment/runtime error). Category: Deployment.

Common causes

• GitHub vercel/next.js issues #93852 (#93850) reported May 2026 with minimal repro. Local build succeeds but Vercel deploy fails with HTTP 500. Blocking production deployments for teams using Next.js 16.2.x + sentry. Not in covered-errors (only generic ‘Vercel build failed’ exists, this is a specific deployment/runtime error). Category: Deployment.

Quick fixes

1. Confirm the exact error signature matches MIDDLEWARE_INVOCATION_FAILED: Cannot find module '/var/task/node_modules/@swc/helpers/esm/_interop_require_default.js' — next@16.2.x + proxy.ts + @sentry/nextjs.
2. Check the Vercel 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
• https://github.com/vercel/next.js/issues/93850

Evidence note: GitHub vercel/next.js issues #93852 (#93850) reported May 2026 with minimal repro. Local build succeeds but Vercel deploy fails with HTTP 500. Blocking production deployments for teams using Next.js 16.2.x + sentry. Not in covered-errors (only generic ‘Vercel build failed’ exists, this is a specific deployment/runtime error). Category: Deployment.

Related errors

• Deployment

FAQ

What should I check first?

Start with the exact MIDDLEWARE_INVOCATION_FAILED: Cannot find module '/var/task/node_modules/@swc/helpers/esm/_interop_require_default.js' — next@16.2.x + proxy.ts + @sentry/nextjs text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Vercel 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 '/var/task/node_modules/@swc/helpers/esm/_interop_require_default.js' — next@16.2.x + proxy.ts + @sentry/nextjs.