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Could not establish connection. Receiving end does not exist.

For the last few releases of Fx, I've been sporadically getting the message in the subject when clicking on the icon to open the extension. When this happens, I also notice that Bitwarden gives me a message of "Unfortunately this window is not available in private mode for this browser." and also that uBlock Origin stops working. The browser isn't in private mode... there is no mask icon, and if I simply restart Bitwarden it doesn't complain about private mode. Checker Plus for Calendar isn't affected at all. To recover, I can recycle each extension manually or restart the browser. Over several weeks, after disabling extensions and trying different combinations it appears that that Checker Plus for gmail is triggering the issue. If I disable the gmail extension, the problem goes away. To eliminate gmail itself, I've also tried using the GMail Notifier extension, and when using it, the problem doesn't occur. Do you have any idea what might be causing this, or something I can do to get additional information to debug? I've also reinstalled the extension, reinstalled the browser, etc. and none of that has helped. Thanks!


  • When you say getting the message in the subject, what do you mean? can you send me a screenshot of this error for context.

  • When I click on the Gmail icon in the toolbar, in the popup the following message is displayed:

    Could not establish connection. Receiving end does not exist.

    It is hard to take a screenshot because when I click in another position on my desktop, the popup disappears.

  • I guess the first thing will be to determine the pattern, what % of times you open the popup does it occur, do you have other windows or tabs open, or options windows when you are opening the popup window etc.

  • Yeah, I've tried that... but the only thing I've noticed it that it happens once or twice a day. I haven't been able to detect a pattern. I was hoping you had some kind of trace option I could turn on that would trap it. If you think of something, LMK. In the meantime, I'll keep trying to isolate it.

  • Ok, the next time it happens if you can send me the popup error logs, although I realize with Firefox that's not as easy to filter out the popup only errors: https://jasonsavard.com/wiki/Error_logs

  • When testing how to do the logs, I noticed that the extension keeps generating the error over and over again, but doesn't appear to affect the functionality. At one point however, the hang happens. Here is a screenshot... Just an FYI...

  • Found this definition of the error:

    It means an extension is sending a message that doesn't have a corresponding listener, and not handling the error correctly.

  • edited July 2020

    Ok good data, I noticed that particular line common.js 4617 is referring to saving options.

    But it's possible those errors are not the same one in the popup, the best would be to wait to get the error in the popup window and then send me the logs right after so that we capture that recent error near the end of the logs.

    For my reference:

    wrappedDB.syncExternally = async function(key) {

        chrome.runtime.sendMessage({command:"indexedDBSettingSaved", key:key});


  • Thanks, will do.

  • Here is a snapshot of the log, not sure if this is immediately after it happened. I walked away, came back did a few things and then noticed it had stopped again. If this doesn't help, I'll keep trying to capture. Thanks!

  • ok thanks I do see more logs pertinent to the issue there, i'll add this to the ticket.

  • edited July 17

    Hello! I have the same problem when I try to manually sign in my gmail accounts.

    For reference, I am currently switching from Chrome to Firefox. I run Manjaro on Linux, if that helps as well.


  • @Bree Gutierrez Does the default auto-detect mode work?

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