Hello Vercel Support Team,
I am encountering a sudden application error when opening the Preview deployment of my project. The preview environment loads an error page instead of the app.
Error Message
An application error has occurred while loading
/auth/login
TypeError: Cannot read properties of undefined (reading ‘call’)
The stack trace references a Next.js runtime error inside the compiled preview build (webpack / Next.js runtime). This error appeared unexpectedly — the preview was working earlier and no major structural changes were made immediately before this started occurring.
Observed Behavior
- The preview deployment opens but immediately throws the runtime error.
- The app does not render and the
/auth/loginroute fails. - This only appears in the Preview environment.
- The error originates during module initialization (
options.factory/__webpack_require__).
What I Would Like Help Verifying
- Whether the preview build environment may have corrupted cache or dependency resolution.
- If the preview deployment runtime has any known issue related to
Next.jsmodule loading. - Whether clearing the build cache or re-deploying the preview would resolve this.
If necessary, I can also provide:
- Deployment URL
- Commit hash
- Project ID
- Build logs
Please let me know what additional details would help diagnose this issue.
Thank you.