Using next/font results in Font loader calls must be assigned to a const in Pages Router #86792
Description
Link to the code that reproduces this issue
https://github.com/jonahallibone/next-font-bug
To Reproduce
npm installnpm run dev- Error
Current vs. Expected behavior
I don't expect an error
Provide environment information
Operating System:
Platform: darwin
Arch: arm64
Version: Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:29 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6000
Available memory (MB): 32768
Available CPU cores: 10
Binaries:
Node: 24.11.1
npm: 11.6.2
Yarn: 1.22.19
pnpm: 9.6.0
Relevant Packages:
next: 16.0.7 // Latest available version is detected (16.0.7).
eslint-config-next: N/A
react: 19.2.1
react-dom: 19.2.1
typescript: 5.9.3
Next.js Config:
output: N/AWhich area(s) are affected? (Select all that apply)
Turbopack
Which stage(s) are affected? (Select all that apply)
next dev (local)
Additional context
This was happening in our monorepo on one project, so I extracted the project and progressively brought it down to this reproduction
The error is
Build Error
Ecmascript file had an error
./src/pages/_app.tsx (4:1)
Ecmascript file had an error
2 | import { Inter } from "next/font/google";
3 |
> 4 | const inter = Inter({ subsets: ["latin"] });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
5 |
6 | export default function App({ Component, pageProps }: AppProps) {
7 | return (
Font loader calls must be assigned to a constThings I have tried:
- Moving font definitions into a module and importing them
- Removing almost all of our other dependencies
The resolution is to not use next/font at all. Once this starts to happen, it is also incredibly difficult to undo, because the cause is unknown. There is also very little in way of errors. The console only reports a 500 on the route, and the browser console logs the same error as in the overlay. I assume, based on the error, that this is a problem with SWC. I am only able to reproduce this by paring down my project. Fresh installations of Next.js work completely fine. I am assuming this is related to some other dependency.