vercel/next.js · error

[Next.js Unhandled Rejection Filter]: ${message}

Error message

[Next.js Unhandled Rejection Filter]: ${message}

What it means

Log line emitted by the Next.js unhandled-rejection filter's logging helpers. During setup, a switch on UHR_FILTER_LOG_LEVEL assigns warn/warnWithTrace/debug functions; this message is the formatted rejection reason being surfaced at the configured 'warn' level after the filter decided to log (rather than suppress) an unhandled promise rejection in the dev server process.

Source

Thrown at packages/next/src/server/node-environment-extensions/unhandled-rejection.external.tsx:80

    }
}

let debug: typeof console.debug | undefined
let debugWithTrace: typeof console.debug | undefined
let warn: typeof console.warn | undefined
let warnWithTrace: typeof console.warn | undefined

switch (UHR_FILTER_LOG_LEVEL) {
  case 'debug':
    debug = (message: string) =>
      console.log('[Next.js Unhandled Rejection Filter]: ' + message)
    debugWithTrace = (message: string) => {
      console.log(new DebugWithStack(message))
    }
  // Intentional fallthrough
  case 'warn':
    warn = (message: string) => {
      console.warn('[Next.js Unhandled Rejection Filter]: ' + message)
    }
    warnWithTrace = (message: string) => {
      console.warn(new WarnWithStack(message))
    }
    break
  case 'silent':
  default:
}

class DebugWithStack extends Error {
  constructor(message: string) {
    super(message)
    this.name = '[Next.js Unhandled Rejection Filter]'
  }
}

class WarnWithStack extends Error {
  constructor(message: string) {

View on GitHub (pinned to 0eb3775416)

Solutions

1. Handle the rejected promise in your code (add .catch or try/await) so the rejection is not unhandled.

When it happens

Trigger: Thrown at packages/next/src/server/node-environment-extensions/unhandled-rejection.external.tsx:80 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/615da235661eed5c. Report an issue: GitHub.