`browser.runtime.sendMessage` throws "no connection" error when popup is trying to talk to terminated background event page

Add-ons Development
#1

To reproduce this error:

Manifest version 3

In popup (“action”) a button click invokes chrome.runtime.sendMessage.
The background script is listening to it via chrome.runtime.onMessage.addListener and will open some extension page (i.e. settings page or contact page) in the callback.

But:
The promise returned by chrome.runtime.sendMessage will be rejected with "Could not establish connection. Receiving end does not exist." if the background went idle/stopped running and its event page got terminated, so that the user has to click the popup button twice (since the first attempt will trigger the background and re-activate it).

How should this be dealt with?

As a workaround I could always try a second time to send the message(?) - but I’m sure there’s a saner way to handle this issue…

I think more generally speaking the issue is with not having persistent background scripts anymore in v3 and the lack of experience on how to handle non-persistent bg scripts.

#2

Oooh, I see now!

So, it seems the background script gets executed each time it starts running again.
The problem in my case was that I do some async storage initialization and only after that I register the listener to listen to messages from elsewhere.

The fix then is: Register the listener in the background script right away (sync) and not postponed (i.e. after an async op).

Side note: The async initialization stuff shouldn’t even be executed multiple times during a single browser session -> can be safely moved to the callback of chrome.runtime.onInstalled.addListener.

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