1595017 - [devtool] [responsive design mode] Incorrect user-agent on responsive design mode

Status: NEW

(DevTools :: Responsive Design Mode, defect, P2)

Description

[Tripurari Shankar]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:71.0) Gecko/20100101 Firefox/71.0

Steps to reproduce:

Steps to reproduce

1. Open Firefox Nightly
2. Open any website
3. Select responsive design mode and choose any mobile device in responsive design mode
4. try reloading the page

Actual results:

You can see selecting responsive design mode will have no effect on the website ( still shows the desktop version )
because the user-agent header sent in HTTP request does not change

Expected results:

Should have open the mobile version of the website and the user-agent in HTTP request should have been changed according to selected device

Comment 1

[Tripurari Shankar]

Attachment: user-agent-bug-2.gif

Comment 2

[Gingerbread Man]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0
20191107215315

The following works for me:

1. https://www.flipkart.com
2. Open Responsive Design Mode.
3. Select Edit List and check iPhone 5/SE, then click the Close button.
4. Select iPhone 5/SE.
5. Open the developer tools, Network category and click the Reload button there.

Actual results:
Request headers lists
User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 10_3_1 like Mac OS X) AppleWebKit/603.1.30 (KHTML, like Gecko) Version/10.0 Mobile/14E304 Safari/602.1

Comment 3

[Patrick Brosset <:pbro>]

I can confirm that, sometimes, the user-agent string is not sent to the server.
Sometimes I just have to choose another device, and then it gets sent and I get the proper mobile version for the site.
Even after that, if I then switch to another device, I may be getting the desktop version of it.