[Bug]: Official trace-viewer (trace.playwright.dev) now refusing to load traces on local network

[splint33]

Version

latest

Steps to reproduce

Host, on a https server, a playwright trace file.
With Google Chrome < v142, try to load the trace with the URL trace parameter, like this:
https://trace.playwright.dev/?trace=https://xxxx//playwright_trace.zip
File load fine.
With Google Chrome > v142, and with the flag #local-network-access-check unset, try to load the file like previously.
No popup asking access to local network access is shown and the trace does not load.
Setting the chrome flag to disabled fixes the issue.

Expected behavior

A popup asking for local network access is shown to the user.
If he accept, the trace load.
If he denies, the trace does not load and an error is shown.

I expect a behavior similar to shown in this example website, with a popup:
https://lna-testing.notyetsecure.com/

Actual behavior

No popup, the trace does not load unless the user set the chrome flag #local-network-access-check to disabled.

Additional context

This problem appeared following changes made into chromium 142, with a detailled documentation here:
https://docs.google.com/document/d/1QQkqehw8umtAgz5z0um7THx-aoU251p705FbIQjDuGs/edit?pli=1&tab=t.0

Environment

System:
    OS: Windows 11 10.0.26200
    CPU: (20) x64 13th Gen Intel(R) Core(TM) i7-13800H
    Memory: 15.55 GB / 31.69 GB
  Binaries:
    Node: 20.17.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.22.0 - C:\Users\xxx\AppData\Roaming\npm\pnpm.CMD
  Languages:
    Bash: 5.2.26 - C:\Program Files\Git\bin\bash.EXE

[Skn0tt]

If it's caused by a Chrome change, I'm not sure what Playwright can do about it. You probably can make it work by properly configuring CORS on your server, right?

[splint33]

On the test website I gave, I have no issues loading the same .zip file from my https server, after accepting the new chrome popup.
trace.playwright.dev doesn't seem to ask for any local-network-access, so chrome is now blocking by default the request.
While fetching the trace file, I think we may be able to do the same, by prompting the user with a popup for LNA.

[Skn0tt]

I don't understand how localhost is involved. Is the HTTPS server on localhost?

[splint33]

Sorry if I'm not clear enough, English is not my primary language.

I have a XAMPP server hosted on my private company server.
This server has signed certificates by our company, and is accessed by its hostname in the company domain, let's say https://server.ad.company.net:444. The resolved IP address is in the 172.16.. ip range.
This webserver is used to host test results, view test logs, and view playwright logs.

I used to be able to browse logs by using the following URL:
https://trace.playwright.dev/?trace=https://server.ad.company.net:444/playwright_reports/report_XXX.zip.

It was working well, but since chrome 142 changes, loading a local network from a public network (https://server.ad.company.net:444 from https://trace.playwright.dev) is now blocked by default.

Chrome have provided a user-friendly way to still be able to do so, by requesting the user, with a dialog, to access local network

I've tested this feature on the same local network, from the example website https://lna-testing.notyetsecure.com/, and it's working, prompting me with a dialog to allow the access, as shown, and loading the content from my private network when granted.

I believe that the official trace website may be able to show the same prompt to ensure the same compatibility as before.

Thanks a lot for your time

[Skn0tt]

Ahh, thanks for elaborating! Now I understand the problem. I couldn't reproduce it in Edge, but it's a Chrome-exclusive behaviour currently! Thanks. I'll see what we can do.

[Skn0tt]

We're not able to open the permission prompt for reason i'm explaining in #38221, but we can show a hint about local network access. Could you check out the demo video & deploy preview link in the PR and let me know if that also solves your usecase? I was only able to test with localhost, not with a company-private IP range.

[splint33]

Of course, i'll give it a try as soon as I can, thanks again !
I think I've read something about LNA exclusions for localhost and some ip range, such as 192.*

[splint33]

I can confirm that the LNA error is only shown if the trace fail to load and the LNA permission is not granted.
If the permission is granted and the log still fail to load, the LNA specific part is not shown.

As you've mentionned, it looks like LNA popups cannot currently be requested by a worker, but needs to be triggered by the application in order for the worker to gain LNA, as stated in this blog post:
https://developer.chrome.com/blog/local-network-access#chrome_138

Thanks again for your time

[Skn0tt]

Nice! Just to confirm, are you able to load the trace from your company servers after granting the permission?

[splint33]

My bad, yes, after editing my company server to allow your test server, the trace file loads just fine