nextjs - 💡(How to fix) Fix userAgent device.type is undefined for Macos Apple silicon devices [1 comments, 2 participants]

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vercel/next.js#87236Fetched 2026-04-08 02:07:32
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Code Example

Operating System: MacOs 26.1
Browser: Chrome, Safari
pnpm: 10.18.3
node: 22.19.0
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Link to the code that reproduces this issue

https://github.com/Milad1412/reproduce_device_detection_issue

To Reproduce

  1. On a MacOs device start application in either production or dev mode
  2. see the log and you find the issue that device.type is undefined in the console log of server's terminal

Current vs. Expected behavior

I expect to see a valid value for type of device, while I see undefined on Mac.

Provide environment information

Operating System: MacOs 26.1
Browser: Chrome, Safari
pnpm: 10.18.3
node: 22.19.0

Which area(s) are affected? (Select all that apply)

Middleware

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local)

Additional context

No response

extent analysis

TL;DR

  • The issue with device.type being undefined on MacOs devices may be related to middleware configuration or device detection logic, and verifying the device detection code is the first step towards a solution.

Guidance

  • Review the device detection middleware code to ensure it correctly handles MacOs devices and extracts the device.type property.
  • Verify that the device object is being populated correctly before attempting to access its type property.
  • Check the browser's user agent string to see if it provides any clues about the device type, which might be used to infer the device.type value.
  • Test the application on different MacOs versions and browsers to see if the issue is specific to certain environments.

Example

  • No specific code example can be provided without more context, but the device detection logic might involve parsing the user agent string, such as const userAgent = req.headers['user-agent'];.

Notes

  • The issue might be specific to the MacOs environment or the versions of Chrome and Safari being used.
  • Without more information about the device detection code, it's difficult to provide a more specific solution.

Recommendation

  • Apply workaround: The best course of action is to implement a workaround that involves manually setting the device.type value based on the user agent string or other available information, as the root cause of the issue is unclear.

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nextjs - 💡(How to fix) Fix userAgent device.type is undefined for Macos Apple silicon devices [1 comments, 2 participants]