Lighthouse passes inconsistent User Agent on Redirect

FAQ

• Yes, my issue is not about variability or throttling.
• Yes, my issue is not about a specific accessibility audit (file with axe-core instead).

URL

https://www.etsy.com/listing/1041475753

What happened?

Lighthouse passes a different UA than chrome dev tools, causing subtle odd bugs with device detection.

Lighthouse: Mozilla/5.0 (Linux; Android 7.0; Moto G (4)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4590.2 Mobile Safari/537.36 Chrome-Lighthouse

Chrome: Mozilla/5.0 (Linux; Android 6.0.1; Moto G (4)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Mobile Safari/537.36

What did you expect?

We see the same user agent exactly for easier debugging.

What have you tried?

I checked the Etsy server logs to validate that the user agents differ.

How were you running Lighthouse?

Chrome DevTools

Lighthouse Version

8.4.0

Chrome Version

95

Node Version

No response

OS

Mac

Relevant log output

No response

[broguinn]

@paulirish That’s a fair estimation of what’s going on - DeviceAtlas’ return value for any Moto G4 user agent I’ve tested seems to be a mobile device, but not a mobile phone. And accordingly, we’re having to change our internal device identification logic to check either field.

To be clear, I don’t think the issue of slight variations between Chrome device emulation’s Moto G4 user agent and the one sent by Lighthouse are an issue for our use case. For pure debugging purposes, I was surprised that they weren’t identical. If it’s relatively simple to sync the android and chrome versions here, that would be a satisfying level of internal consistency.

Thanks a bunch!

[jav666]

its the same here. my UA (emulated):

Mozilla/5.0 (Linux; Android 6.0.1; Moto G (4)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Mobile Safari/537.36

after redirect:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36