Next.js 15.5.4 Build Fails: context.params Type Mismatch on Vercel

[mandaldebangshu7-commits]

Link to the code that reproduces this issue

https://github.com/unknownentity00-tech/TravelBlog.git

To Reproduce

1.deploy this project using next.js in vercel
2. Preview: https://blogtravel-f6e13jae4-mandaldebangshu7-7178s-projects.vercel.app [5s]
2025-09-24T15:52:37.256Z Running build in Washington, D.C., USA (East) – iad1
2025-09-24T15:52:37.256Z Build machine configuration: 2 cores, 8 GB
2025-09-24T15:52:37.272Z Retrieving list of deployment files...
2025-09-24T15:52:37.275Z Skipping build cache, deployment was triggered without cache.
2025-09-24T15:52:37.761Z Downloading 74 deployment files...
2025-09-24T15:52:38.401Z Running "vercel build"
2025-09-24T15:52:38.889Z Vercel CLI 48.1.1
2025-09-24T15:52:39.292Z Installing dependencies...
2025-09-24T15:52:43.818Z npm warn deprecated q@1.5.1: You or someone you depend on is using Q, the JavaScript Promise library that gave JavaScript developers strong feelings about promises. They can almost certainly migrate to the native JavaScript promise now. Thank you literally everyone for joining me in this bet against the odds. Be excellent to each other.
2025-09-24T15:52:43.819Z npm warn deprecated
2025-09-24T15:52:43.820Z npm warn deprecated (For a CapTP with native promises, see @endo/eventual-send and @endo/captp)
2025-09-24T15:53:02.903Z
2025-09-24T15:53:02.904Z added 514 packages in 23s
2025-09-24T15:53:02.905Z
2025-09-24T15:53:02.905Z 151 packages are looking for funding
2025-09-24T15:53:02.906Z run npm fund for details
2025-09-24T15:53:02.945Z Detected Next.js version: 15.5.4
2025-09-24T15:53:02.951Z Running "npm run build"
2025-09-24T15:53:03.057Z
2025-09-24T15:53:03.057Z > blogtravel@0.1.0 build
2025-09-24T15:53:03.057Z > next build --turbopack
2025-09-24T15:53:03.057Z
2025-09-24T15:53:03.813Z ⚠ Invalid next.config.ts options detected:
2025-09-24T15:53:03.813Z ⚠ Unrecognized key(s) in object: 'serverComponentsExternalPackages' at "experimental"
2025-09-24T15:53:03.813Z ⚠ See more info here: https://nextjs.org/docs/messages/invalid-next-config
2025-09-24T15:53:03.815Z ⚠ experimental.serverComponentsExternalPackages has been moved to serverExternalPackages. Please update your next.config.ts file accordingly.
2025-09-24T15:53:03.822Z Attention: Next.js now collects completely anonymous telemetry regarding usage.
2025-09-24T15:53:03.822Z This information is used to shape Next.js' roadmap and prioritize features.
2025-09-24T15:53:03.823Z You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
2025-09-24T15:53:03.823Z https://nextjs.org/telemetry
2025-09-24T15:53:03.823Z
2025-09-24T15:53:03.874Z ▲ Next.js 15.5.4 (Turbopack)
2025-09-24T15:53:03.875Z - Environments: .env
2025-09-24T15:53:03.875Z - Experiments (use with caution):
2025-09-24T15:53:03.875Z · serverComponentsExternalPackages
2025-09-24T15:53:03.875Z
2025-09-24T15:53:03.970Z Creating an optimized production build ...
2025-09-24T15:53:18.954Z ✓ Finished writing to disk in 35ms
2025-09-24T15:53:18.980Z ✓ Compiled successfully in 14.3s
2025-09-24T15:53:18.992Z Linting and checking validity of types ...
2025-09-24T15:53:24.423Z
2025-09-24T15:53:24.424Z ./src/types/next.d.ts
2025-09-24T15:53:24.424Z 1:15 Warning: 'NextRequest' is defined but never used. @typescript-eslint/no-unused-vars
2025-09-24T15:53:24.424Z
2025-09-24T15:53:24.424Z info - Need to disable some ESLint rules? Learn more here: https://nextjs.org/docs/app/api-reference/config/eslint#disabling-rules
2025-09-24T15:53:27.538Z Failed to compile.
2025-09-24T15:53:27.539Z
2025-09-24T15:53:27.539Z Type error: Type 'typeof import("/vercel/path0/src/app/api/profile-data/[id]/route")' does not satisfy the constraint 'RouteHandlerConfig<"/api/profile-data/[id]">'.
2025-09-24T15:53:27.540Z Types of property 'GET' are incompatible.
2025-09-24T15:53:27.540Z Type '(request: NextRequest, context: { params: { id: string; }; }) => Promise<NextResponse<{ error: string; }> | NextResponse<{ posts: ({ likes: { id: string; createdAt: Date; userId: string; postId: string; }[]; comments: { ...; }[]; } & { ...; })[]; followers: number; following: number; }>>' is not assignable to type '(request: NextRequest, context: { params: Promise<{ id: string; }>; }) => void | Response | Promise<void | Response>'.
2025-09-24T15:53:27.541Z Types of parameters 'context' and 'context' are incompatible.
2025-09-24T15:53:27.542Z Type '{ params: Promise<{ id: string; }>; }' is not assignable to type '{ params: { id: string; }; }'.
2025-09-24T15:53:27.542Z Types of property 'params' are incompatible.
2025-09-24T15:53:27.542Z Property 'id' is missing in type 'Promise<{ id: string; }>' but required in type '{ id: string; }'.
2025-09-24T15:53:27.543Z
2025-09-24T15:53:27.562Z Next.js build worker exited with code: 1 and signal: null
2025-09-24T15:53:27.585Z Error: Command "npm run build" exited with 1
debangshumandal@DEBANGSHUs-MacBook-Air blogtravel % vercel --force
Vercel CLI 48.1.4
🔍 Inspect: https://vercel.com/mandaldebangshu7-7178s-projects/blogtravel/BibtTdx4335Nb5tjg4zChbRPFbaY [5s]
✅ Preview: https://blogtravel-qljdjtayg-mandaldebangshu7-7178s-projects.vercel.app [5s]
2025-09-24T15:56:13.064Z Running build in Washington, D.C., USA (East) – iad1
2025-09-24T15:56:13.064Z Build machine configuration: 2 cores, 8 GB
2025-09-24T15:56:13.081Z Retrieving list of deployment files...
2025-09-24T15:56:13.085Z Skipping build cache, deployment was triggered without cache.
2025-09-24T15:56:13.600Z Downloading 74 deployment files...
2025-09-24T15:56:14.251Z Running "vercel build"
2025-09-24T15:56:14.624Z Vercel CLI 48.1.1
2025-09-24T15:56:14.930Z Installing dependencies...
2025-09-24T15:56:17.954Z npm warn deprecated q@1.5.1: You or someone you depend on is using Q, the JavaScript Promise library that gave JavaScript developers strong feelings about promises. They can almost certainly migrate to the native JavaScript promise now. Thank you literally everyone for joining me in this bet against the odds. Be excellent to each other.
2025-09-24T15:56:17.955Z npm warn deprecated
2025-09-24T15:56:17.955Z npm warn deprecated (For a CapTP with native promises, see @endo/eventual-send and @endo/captp)
2025-09-24T15:56:35.303Z
2025-09-24T15:56:35.303Z added 514 packages in 20s
2025-09-24T15:56:35.304Z
2025-09-24T15:56:35.307Z 151 packages are looking for funding
2025-09-24T15:56:35.307Z run npm fund for details
2025-09-24T15:56:35.374Z Detected Next.js version: 15.5.4
2025-09-24T15:56:35.380Z Running "npm run build"
2025-09-24T15:56:35.493Z
2025-09-24T15:56:35.493Z > blogtravel@0.1.0 build
2025-09-24T15:56:35.494Z > next build --turbopack
2025-09-24T15:56:35.494Z
2025-09-24T15:56:36.288Z ⚠ Invalid next.config.ts options detected:
2025-09-24T15:56:36.289Z ⚠ Unrecognized key(s) in object: 'serverComponentsExternalPackages' at "experimental"
2025-09-24T15:56:36.289Z ⚠ See more info here: https://nextjs.org/docs/messages/invalid-next-config
2025-09-24T15:56:36.290Z ⚠ experimental.serverComponentsExternalPackages has been moved to serverExternalPackages. Please update your next.config.ts file accordingly.
2025-09-24T15:56:36.297Z Attention: Next.js now collects completely anonymous telemetry regarding usage.
2025-09-24T15:56:36.297Z This information is used to shape Next.js' roadmap and prioritize features.
2025-09-24T15:56:36.297Z You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
2025-09-24T15:56:36.298Z https://nextjs.org/telemetry
2025-09-24T15:56:36.298Z
2025-09-24T15:56:36.347Z ▲ Next.js 15.5.4 (Turbopack)
2025-09-24T15:56:36.348Z - Environments: .env
2025-09-24T15:56:36.348Z - Experiments (use with caution):
2025-09-24T15:56:36.349Z · serverComponentsExternalPackages
2025-09-24T15:56:36.349Z
2025-09-24T15:56:36.434Z Creating an optimized production build ...
2025-09-24T15:56:49.503Z ✓ Finished writing to disk in 30ms
2025-09-24T15:56:49.537Z ✓ Compiled successfully in 12.5s
2025-09-24T15:56:49.542Z Linting and checking validity of types ...
2025-09-24T15:56:54.334Z
2025-09-24T15:56:54.334Z ./src/types/next.d.ts
2025-09-24T15:56:54.335Z 1:15 Warning: 'NextRequest' is defined but never used. @typescript-eslint/no-unused-vars
2025-09-24T15:56:54.335Z
2025-09-24T15:56:54.335Z info - Need to disable some ESLint rules? Learn more here: https://nextjs.org/docs/app/api-reference/config/eslint#disabling-rules
2025-09-24T15:56:57.207Z Failed to compile.
2025-09-24T15:56:57.207Z
2025-09-24T15:56:57.208Z Type error: Type 'typeof import("/vercel/path0/src/app/api/user-posts/[id]/route")' does not satisfy the constraint 'RouteHandlerConfig<"/api/user-posts/[id]">'.
2025-09-24T15:56:57.209Z Types of property 'GET' are incompatible.
2025-09-24T15:56:57.209Z Type '(request: Request, { params }: { params: { id: string; }; }) => Promise<NextResponse<{ error: string; }> | NextResponse<({ likes: { id: string; createdAt: Date; userId: string; postId: string; }[]; comments: { ...; }[]; } & { ...; })[]>>' is not assignable to type '(request: NextRequest, context: { params: Promise<{ id: string; }>; }) => void | Response | Promise<void | Response>'.
2025-09-24T15:56:57.209Z Types of parameters '__1' and 'context' are incompatible.
2025-09-24T15:56:57.209Z Type '{ params: Promise<{ id: string; }>; }' is not assignable to type '{ params: { id: string; }; }'.
2025-09-24T15:56:57.210Z Types of property 'params' are incompatible.
2025-09-24T15:56:57.210Z Property 'id' is missing in type 'Promise<{ id: string; }>' but required in type '{ id: string; }'.
2025-09-24T15:56:57.210Z
2025-09-24T15:56:57.230Z Next.js build worker exited with code: 1 and signal: null
2025-09-24T15:56:57.251Z Error: Command "npm run build" exited with 1

this will be shown

Current vs. Expected behavior

Current Behavior
The build process fails with a type error during compilation. The error message indicates that the context.params object in the GET route handler is not a Promise as expected by my code. This prevents the application from compiling and deploying.

Expected Behavior
The build should succeed without any type errors. My code correctly handles the new asynchronous behavior of context.params in Next.js 15+ by using await. The framework's build process should recognize and accept the Promise type for context.params, allowing the application to compile and function as intended.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:51 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T8112
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 24.3.0
  npm: 11.5.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.5.4 // Latest available version is detected (15.5.4).
  eslint-config-next: 15.5.3
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.5.4
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Not sure

Which stage(s) are affected? (Select all that apply)

next build (local)

Additional context

Platform: I am deploying the application on Vercel.

Reproducibility: The build fails both on my local machine (macOS) and on the Vercel platform. I have attached the full error logs from both environments.

Technical Details:

Next.js Version: 15.5.4

Node.js Version: (Your Node version, e.g., 20.10.0)

Build Tool: Turbopack (--turbopack)

The error appears to be a type mismatch where my code correctly uses await context.params (as expected in Next.js 15+), but the build process throws an error saying params is not a Promise. This suggests a potential inconsistency in the internal type definitions of the Next.js beta version. I have provided a link to a minimal repository that reproduces this exact issue.

[icyJoseph]

The build error is correct. Here, you are using the sync access pattern:

• https://github.com/unknownentity00-tech/TravelBlog/blob/abdb60af63f65365bfe46c76b1a4167a6d7d3020/src/app/api/user-posts/%5Bid%5D/route.ts#L6-L8

export async function GET(request: Request, { params }: { params: { id: string } }) {
    const { id } = params;

In contrast, here:

• https://github.com/unknownentity00-tech/TravelBlog/blob/abdb60af63f65365bfe46c76b1a4167a6d7d3020/src/app/api/user-metrics/%5Bid%5D/route.ts#L6-L13

export async function GET(
    request: Request,
    // Change the type of 'params' to be a Promise
    { params }: { params: Promise<{ id: string }> }
) {
    try {
        // Await the params object to get the resolved value
        const { id } = await params;

You are using the expected Async access pattern. Your build error is expected on the first route I list here. I haven't checked if you have more of these.

[mandaldebangshu7-commits]

I HAVE MODIFIED USE THIS CODE export async function GET(
request: Request,
// Change the type of 'params' to be a Promise
{ params }: { params: Promise<{ id: string }> }
) {
try {
// Await the params object to get the resolved value
const { id } = await params; STILL SHOWING THE SAME ERROR AND I ALCO DELTED THE CATCH FILES AND IT WAS SHOWING THE SAME ERROR

[icyJoseph]

This file, src/app/api/user-posts/[id]/route.ts, is still not correct:

export async function GET(request: Request, { params }: { params: { id: string } }) {
    const { id } = params;

[mandaldebangshu7-commits]

import { NextRequest, NextResponse } from "next/server";
import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

export async function GET(
request: NextRequest,
{ params }: { params: { id: string } } // Simplified type for context/params
) {
// Destructure 'id' directly from 'params'
const { id: clerkId } = params;

if (!clerkId) {
// This check is often redundant in typical route structures like /api/users/[id]
// but is kept for safety based on the original code's logic.
return NextResponse.json({ error: "User ID is required." }, { status: 400 });
}

try {
const user = await prisma.user.findUnique({ where: { clerkId } });

if (!user) {
  return NextResponse.json(
    { error: "User not found in database." },
    { status: 404 }
  );
}

const posts = await prisma.post.findMany({
  where: { userId: user.id },
  orderBy: { createdAt: "desc" },
  include: {
    likes: true,
    comments: true,
  },
});

const followersCount = await prisma.follow.count({
  where: { followingId: user.id },
});

const followingCount = await prisma.follow.count({
  where: { followerId: user.id },
});

return NextResponse.json(
  {
    posts,
    followers: followersCount,
    following: followingCount,
  },
  { status: 200 }
);

} catch (error) {
console.error("Error fetching user data:", error);
return NextResponse.json(
{ error: "Failed to fetch user data." },
{ status: 500 }
);
}
} i am using this code still showing this error

debangshumandal@DEBANGSHUs-MacBook-Air blogtravel % vercel --force
Vercel CLI 48.1.4
🔍 Inspect: https://vercel.com/mandaldebangshu7-7178s-projects/blogtravel/8fomiytMU2WivH8yehkT633rvDRR [4s]
✅ Preview: https://blogtravel-gmswwvxxx-mandaldebangshu7-7178s-projects.vercel.app [4s]
2025-09-25T14:58:37.562Z Running build in Washington, D.C., USA (East) – iad1
2025-09-25T14:58:37.563Z Build machine configuration: 2 cores, 8 GB
2025-09-25T14:58:37.631Z Retrieving list of deployment files...
2025-09-25T14:58:37.634Z Skipping build cache, deployment was triggered without cache.
2025-09-25T14:58:38.127Z Downloading 118 deployment files...
2025-09-25T14:58:39.003Z Running "vercel build"
2025-09-25T14:58:39.632Z Vercel CLI 48.1.6
2025-09-25T14:58:39.991Z Installing dependencies...
2025-09-25T14:58:43.931Z npm warn deprecated q@1.5.1: You or someone you depend on is using Q, the JavaScript Promise library that gave JavaScript developers strong feelings about promises. They can almost certainly migrate to the native JavaScript promise now. Thank you literally everyone for joining me in this bet against the odds. Be excellent to each other.
2025-09-25T14:58:43.932Z npm warn deprecated
2025-09-25T14:58:43.932Z npm warn deprecated (For a CapTP with native promises, see @endo/eventual-send and @endo/captp)
2025-09-25T14:59:00.682Z
2025-09-25T14:59:00.683Z added 514 packages in 20s
2025-09-25T14:59:00.683Z
2025-09-25T14:59:00.683Z 151 packages are looking for funding
2025-09-25T14:59:00.684Z run npm fund for details
2025-09-25T14:59:00.891Z Detected Next.js version: 15.5.4
2025-09-25T14:59:00.897Z Running "npm run build"
2025-09-25T14:59:01.012Z
2025-09-25T14:59:01.013Z > blogtravel@0.1.0 build
2025-09-25T14:59:01.013Z > next build --turbopack
2025-09-25T14:59:01.013Z
2025-09-25T14:59:01.866Z ⚠ Invalid next.config.ts options detected:
2025-09-25T14:59:01.867Z ⚠ Unrecognized key(s) in object: 'serverComponentsExternalPackages' at "experimental"
2025-09-25T14:59:01.868Z ⚠ See more info here: https://nextjs.org/docs/messages/invalid-next-config
2025-09-25T14:59:01.871Z ⚠ experimental.serverComponentsExternalPackages has been moved to serverExternalPackages. Please update your next.config.ts file accordingly.
2025-09-25T14:59:01.882Z Attention: Next.js now collects completely anonymous telemetry regarding usage.
2025-09-25T14:59:01.883Z This information is used to shape Next.js' roadmap and prioritize features.
2025-09-25T14:59:01.883Z You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
2025-09-25T14:59:01.884Z https://nextjs.org/telemetry
2025-09-25T14:59:01.884Z
2025-09-25T14:59:01.998Z ▲ Next.js 15.5.4 (Turbopack)
2025-09-25T14:59:01.999Z - Environments: .env
2025-09-25T14:59:02.000Z - Experiments (use with caution):
2025-09-25T14:59:02.000Z · serverComponentsExternalPackages
2025-09-25T14:59:02.001Z
2025-09-25T14:59:02.202Z Creating an optimized production build ...
2025-09-25T14:59:15.042Z ✓ Finished writing to disk in 34ms
2025-09-25T14:59:15.071Z ✓ Compiled successfully in 12.2s
2025-09-25T14:59:15.076Z Linting and checking validity of types ...
2025-09-25T14:59:19.822Z
2025-09-25T14:59:19.823Z ./src/types/next.d.ts
2025-09-25T14:59:19.823Z 1:15 Warning: 'NextRequest' is defined but never used. @typescript-eslint/no-unused-vars
2025-09-25T14:59:19.823Z
2025-09-25T14:59:19.823Z info - Need to disable some ESLint rules? Learn more here: https://nextjs.org/docs/app/api-reference/config/eslint#disabling-rules
2025-09-25T14:59:22.786Z Failed to compile.
2025-09-25T14:59:22.788Z
2025-09-25T14:59:22.789Z Type error: Type 'typeof import("/vercel/path0/src/app/api/profile-data/[id]/route")' does not satisfy the constraint 'RouteHandlerConfig<"/api/profile-data/[id]">'.
2025-09-25T14:59:22.789Z Types of property 'GET' are incompatible.
2025-09-25T14:59:22.790Z Type '(request: NextRequest, { params }: { params: { id: string; }; }) => Promise<NextResponse<{ error: string; }> | NextResponse<{ posts: ({ likes: { id: string; createdAt: Date; userId: string; postId: string; }[]; comments: { ...; }[]; } & { ...; })[]; followers: number; following: number; }>>' is not assignable to type '(request: NextRequest, context: { params: Promise<{ id: string; }>; }) => void | Response | Promise<void | Response>'.
2025-09-25T14:59:22.791Z Types of parameters '__1' and 'context' are incompatible.
2025-09-25T14:59:22.791Z Type '{ params: Promise<{ id: string; }>; }' is not assignable to type '{ params: { id: string; }; }'.
2025-09-25T14:59:22.791Z Types of property 'params' are incompatible.
2025-09-25T14:59:22.791Z Property 'id' is missing in type 'Promise<{ id: string; }>' but required in type '{ id: string; }'.
2025-09-25T14:59:22.792Z
2025-09-25T14:59:22.817Z Next.js build worker exited with code: 1 and signal: null
debangshumandal@DEBANGSHUs-MacBook-Air blogtravel %

https://github.com/unknownentity00-tech/TravelBlog.git

[icyJoseph]

Now, src/app/api/profile-data/[id]/route.ts:

export async function GET(
  request: NextRequest,
  { params }: { params: { id: string } } // Simplified type for context/params
) {

Is not using the Async access. You have to fix all routes, you can do npm run build locally, no need to push to Vercel to see these errors.