vercel/next.js · error

`experimental.${oldExperimentalKey}` has been moved to `${ne

Error message

`experimental.${oldExperimentalKey}` has been moved to `${newKey}`. Please update your ${configFileName} file accordingly.

What it means

Deprecation warning from warnOptionHasBeenMovedOutOfExperimental during config load: an option still set under config.experimental.<oldExperimentalKey> has been promoted to a top-level key. The warning names both the old experimental path and the new key (with the config file name) so the entry can be moved; the old value is not honored.

Source

Thrown at packages/next/src/server/config.ts:294

    warnOptionHasBeenDeprecated(
      userConfig,
      'experimental.browserDebugInfoInTerminal',
      `\`experimental.browserDebugInfoInTerminal\` has been moved to \`logging.browserToTerminal\`. Please update your ${configFileName} file accordingly.`,
      silent
    )
  }
}

export function warnOptionHasBeenMovedOutOfExperimental(
  config: NextConfig,
  oldExperimentalKey: string,
  newKey: string,
  configFileName: string,
  silent: boolean
) {
  if (config.experimental && oldExperimentalKey in config.experimental) {
    if (!silent) {
      Log.warn(
        `\`experimental.${oldExperimentalKey}\` has been moved to \`${newKey}\`. ` +
          `Please update your ${configFileName} file accordingly.`
      )
    }

    let current = config
    const newKeys = newKey.split('.')
    while (newKeys.length > 1) {
      const key = newKeys.shift()!
      ;(current as any)[key] = (current as any)[key] || {}
      current = (current as any)[key]
    }
    ;(current as any)[newKeys.shift()!] = (config.experimental as any)[
      oldExperimentalKey
    ]
  }

  return config

View on GitHub (pinned to 258b1c1bc0)

Solutions

1. Rename the experimental option in your next.config file to the new top-level key as indicated.

When it happens

Trigger: Thrown at packages/next/src/server/config.ts:261 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@258b1c1bc0 (2026-08-19). Data as JSON: /api/errors/f40c083b8897dc1c. Report an issue: GitHub.