Build fails with .next/types param ghost in app/api/[id]/route.ts – all fixes attempted

[irexio]

Summary

I’m building a production Next.js app (with auth, Prisma, API routes, and dynamic [id] segments) and I’m hitting a persistent build error inside .next/types that won’t go away — despite following every documented and recommended fix.

I’m building a privacy-first, ad-free social platform for families and children. This isn’t experimental — I need to pass a clean build before sharing with users. This ghost-type bug has blocked me for 6+ days and ~70 hours of cleanup work across layout scoping, route retyping, and design rewrites.

I truly appreciate the work the Next.js team is doing, but I need clear direction on how to resolve this properly — and avoid this pain again on the next route.

Thank you 🙏
Mimi (Founder, Cliqstr)
https://cliqstr.com/ (early preview site

Additional information

.next/types/app/api/cliqs/[id]/member-actions/route.ts:166:7
Type error: Type '{ __tag__: "POST"; __param_position__: "second"; __param_type__: { params: { id: string; }; }; }' does not satisfy the constraint 'ParamCheck<RouteContext>'.
  The types of '__param_type__.params' are incompatible between these types.
    Type '{ id: string; }' is missing the following properties from type 'Promise<any>': then, catch, finally, [Symbol.toStringTag]

Example

import { defineRoute } from '@/lib/utils/defineRoute'; import { getCurrentUser } from '@/lib/auth/getCurrentUser'; import { prisma } from '@/lib/prisma'; import { NextResponse } from 'next/server'; import { z } from 'zod'; export const POST = defineRoute<{ id: string }>(async (req, { params }) => { const { id } = params; // logic omitted return NextResponse.json({ success: true }); });

[icyJoseph]

Hi,

I feel like, to be 100% sure, I need to look at your implementation for defineRoute, but I'd imagine it is something like this

import { defineRoute } from '@/lib/utils/defineRoute';
import { getCurrentUser } from '@/lib/auth/getCurrentUser';
import { prisma } from '@/lib/prisma';
import { NextResponse } from 'next/server';
import { z } from 'zod';

export const POST = defineRoute<Promise<{ id: string }>>(
  async (req, { params }) => {
    const { id } = await params;

    return NextResponse.json({ success: true });
  },
);

Since Next 15, the params are accessed through a Promise.

• https://nextjs.org/docs/app/api-reference/file-conventions/route#context-optional

This is part of breaking changes documented here: https://nextjs.org/blog/next-15#async-request-apis-breaking-change

[icyJoseph]

Also, please do report back if you get it work, and any other issues you ran into - We'll get your project to build and deploy.

[irexio]

Thank you so much Joseph! I will check this out. I so appreciate your help!!!

[irexio]

Well your solution was the ghost killer! THANKS SO MUCH! Sadly, we have some other build errors to address. I am hoping we can get a clean repo tomorrow and deploy or more testing. I don't know how many more days of battling, reconstructing routes, pages I could tolerate. You ROCK!

[icyJoseph]

Nice! Do not hesitate to post back here, always happy to help out.

[irexio]

Thank you once again. I am far from done, but I deployed again thanks to you! People like you, helping others - it's amazing. I am so grateful.

[icyJoseph]

Awesome, please don't forget to mark an answered - it helps out others with similar errors.

[irexio]

Thanks - I didn't notice the mark as answered button! You are very thoughtful. I appreciate it.