Thank you for helping make Firefox better. If you are reporting a defect, please complete the following:

What were you doing?

1. Open Firefox
2. Navigate to any website
3. Open Browser Toolbox
4. Open "browser.js" in the Debugger tab of the Browser Toolbox
5. Add a custom log breakpoint to the "BrowserBack" function with a value of "E" (or any other value)
6. Use the Back button to navigate to the previous tab

What happened?

I received a warning of debugee 'self-hosted:180' would run in the Toolbox console

What should have happened?

The "E" character should have been printed in the Toolbox console.

Thank you for the report Tim. I can reproduce on Win10 using the latest m-c build.

I am also attaching a screenshot of what I am seeing in the Console.

Note that the E log as well as the warning are there in my case.

Honza, I'd argue that you can't really reproduce since you can see the logpoint in the console, which Tim is missing (the warning might be because of something else)
I'm able to see the log, both with the MultiProcess Browser Toolbox and the regular old Browser Toolbox.
Tim, can you tell us the title of the Browser Toolbox window, just in case.
Also can you check you don't have any console filter disabled?
You can also open a new Browser Toolbox when focused on the BT, which will "debug" the first BT and check in the console if there isn't anything odd there

True, I though the warning itself is the problem.

Well, I figured out the issue. The "Show Content Messages" checkbox wasn't enabled. I've hit my head on this before and still haven't learned apparently 🙃 After enabling the "Show Content Messages", the "E" log appears as expected.

But yeah, I was using the Multiprocess Browser Toolbox and can confirm the title. I also don't have any console filters disabled.

Is there a way to force the Browser Toolbox to always show content messages?

When you enable it it should stay enabled across browser toolbox restart.
We have some plan to make the Browser Toolbox a bit more useful/explicit for those parent/content thing so it would be less confusing.
We could also automatically turn it on when you add a logpoint on a source living in content process so it's less confusing

(In reply to Nicolas Chevobbe [:nchevobbe] from comment #5)

We have some plan to make the Browser Toolbox a bit more useful/explicit for those parent/content thing so it would be less confusing.
We could also automatically turn it on when you add a logpoint on a source living in content process so it's less confusing

Can you say more about the plan? Definitely interested in what kind of enhancements you have in mind.

(In reply to Brian Grinstead [:bgrins] from comment #6)

Can you say more about the plan? Definitely interested in what kind of enhancements you have in mind.

We're looking into having a dedicated toolbar in the browser toolbox/ browser console that would make specific tools more visible; have radio buttons to switch between debugging everything / only parent process [/ current tab], move the iframe picker there and make it more like a <select> so people know they can focus on specific document, move "disable popup autohide" and l10n settings there, …
I'm starting the work in Bug 1776853, and we might iterate on that based on feedback we get.

For now I'm closing the bug as invalid, and we might have an enhancement to avoid people failing into this.
I feel like the "debug mode" (everything/parent process) will replace the "Show content messages" setting so if you can set a logpoint on a source living in content (meaning you have "debug mode" set to "everything"), they will be displayed in the console