Vercel / Deployment

%%drp internal params leak into generateStaticParams() during Next.js build with Cache Components

Fix internal placeholder param %%drp:slugs:...%% leaking as catch-all segment params during Next.js production build with Cache Components + Parallel Routes, causing prerender failure Includes evidence for Vercel troubleshooting demand.

Source-backed Last updated May 23, 2026 1 source Needs local verification

Category: Deployment
Error signature: Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function
Quick fix: Reduce request pressure, check quota or plan limits, and retry with backoff instead of immediate repeated requests.
Updated: May 23, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Vercel, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function is a Vercel failure pattern reported for developers trying to fix internal placeholder param %%drp:slugs:...%% leaking as catch-all segment params during next.js production build with cache components + parallel routes, causing prerender failure. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub Issue #93897 opened May 16, 2026 by user alexortizl — During Next.js 16.3.0-canary.21 production build with Turbopack + Cache Components + Parallel Routes, internal param placeholder %%drp:slugs:9ca6cb0ae51f1%% leaks into catch-all segment params as string instead of string array. Calling .join() fails with TypeError: c.join is not a function. Blocks production build/export. Areas: Partial Prerendering, Dynamic Routes, Parallel & Intercepting Routes.

Common causes

GitHub Issue #93897 opened May 16, 2026 by user alexortizl — During Next.js 16.3.0-canary.21 production build with Turbopack + Cache Components + Parallel Routes, internal param placeholder %%drp:slugs:9ca6cb0ae51f1%% leaks into catch-all segment params as string instead of string array. Calling .join() fails with TypeError: c.join is not a function. Blocks production build/export. Areas: Partial Prerendering, Dynamic Routes, Parallel & Intercepting Routes.

Quick fixes

Confirm the exact error signature matches Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function.
Check the Vercel account, local tool state, and provider configuration involved in the failing workflow.
Reduce request pressure, check quota or plan limits, and retry with backoff instead of immediate repeated requests.

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

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

Diagnostic flow for this page

Match Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function exactly before applying the quick fix.
Compare the failing environment with Vercel versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function mean in Vercel?

Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function indicates the workflow described by "%%drp internal params leak into generateStaticParams() during Next.js build with Cache Components" failed in a Deployment context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function?

Check whether this cause matches your environment: GitHub Issue #93897 opened May 16, 2026 by user alexortizl — During Next.js 16.3.0-canary.21 production build with Turbopack + Cache Components + Parallel Routes, internal param placeholder %%drp:slugs:9ca6cb0ae51f1%% leaks into catch-all segment params as string instead of string array. Calling .join() fails with TypeError: c.join is not a function. Blocks production build/export. Areas: Partial Prerendering, Dynamic Routes, Parallel & Intercepting Routes.

Is the Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function guidance source-backed?

The "%%drp internal params leak into generateStaticParams() during Next.js build with Cache Components" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function?

For "%%drp internal params leak into generateStaticParams() during Next.js build with Cache Components", avoid applying "Reduce request pressure, check quota or plan limits, and retry with backoff instead of immediate repeated requests." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging Received slug: %%drp:slugs:9ca6cb0ae51f1%% TypeError: c.join is not a function?

For "%%drp internal params leak into generateStaticParams() during Next.js build with Cache Components", collect the failing Vercel command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.