Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

What is moz-extension and what purpose does it serve (Firefox v48.0)?

more options

I have set Firefox v48.0 to not record history in order to effectively achieve private browsing and thus enhance privacy. The only thing that now appears in History is a "moz-extension" in the following format: moz-extension://f111111b1-1111-1fae-1111-ef11111d11be/background.html. I've replaced each of the figures by a "1" so as to simply illustrate the structure. I don't know and have not been able to find out just what the moz-extension is and what purpose it serves here. Thanks heaps.

Chosen solution

Greetings All

Thought I'd just complete the loop and let you know that a couple of days ago I had an email respnse from Awesome Screen Shot which said "The developer will fix it later. Please wait for some time.".

I guess that means we should not hold our collective or individual breaths ........

Regardless, thanks to each of you who contributed insights and suggestions in the quest for a quicker solution.. Great stuff!

With appreciation from Downunder!

Read this answer in context 👍 0

All Replies (20)

more options

Are you using the Classic Theme Restorer extension?

more options

Thanks, the-edmeister. I am not using the Classic Theme Restorer extension. Something else ....... ?  :-)

more options

RHills said

a "moz-extension" in the following format: moz-extension://f111111b1-1111-1fae-1111-ef11111d11be/background.html. I've replaced each of the figures by a "1". . . .

Can you provide the real code? We might be able to look it up.

more options

Thanks to you too Fred McD.

The real code is: moz-extension://f35247b9-3404-4fae-9238-ef74153d79be/background.html. Hope that helps ..... :-)

more options

No results found

more options

f35247b9-3404-4fae-9238-ef74153d79be - looks like the GUID of an extension, but since Fred couldn't find a match "we" need to approach identifying it from a different direction.

RHills said

Thanks, the-edmeister. I am not using the Classic Theme Restorer extension. Something else ....... ?  :-)

What extensions do you have installed?

Or use the nuclear approach - Refresh Firefox.

more options

Thanks to both of you: the-edmeister and FredMcD!!

The five installed extensions are: Ant Video Downloader; Awesome Screen Shot; IM Translator; uBlock Origin; You Tube Flash Video Player.

One factor I didn't make explicit in my original posting is that I only configured Firefox to default to Private Browsing a couple of days ago and that it was at that time that the moz-extension appeared. By way of further background I'll mention that I have been using Firefox as my default browser for ten (?) years and have had these extensions for many of those years.

Many thanks across Ponds and Time Zones!  :-)

more options

Looks like addresses starting with moz-extension do not match the relevant extension:

// All moz-extension URIs use a machine-specific UUID rather than the
// extension's own ID in the host component. This makes it more
// difficult for web pages to detect whether a user has a given add-on
// installed (by trying to load a moz-extension URI referring to a
// web_accessible_resource from the extension). getExtensionUUID
// returns the UUID for a given add-on ID.


Pardon me if this is a dumb question, but what displays if you right-click that entry in history and Open in New Tab?

more options

Thanks Jscher2000.

It ain't a dumb question (as I had just been exploring that myself!!).

What happens on a right-click Open in New Tab? The browser opens a new tab having the address given in the History but the page is blank other than one line of text stating: Text Image Temp Image. That text is not selectable.

Thanks for your interest too!

more options

If you View Source on that page (either Ctrl+u or right-click > View Page Source), does it look at all like this background.html file from uBlock Origin?

If not, is there anything in the pages to indicate it might belong to a different extension?

more options

Appreciate the question, Jscher2000.

Below is a copy of the page source. Line numbers did not copy. I've checked out the URL you gave but am not sufficiently techo to identify relevant (dis)similarities.

<!DOCTYPE html>
	<meta charset="utf-8"/>
    <script type="text/javascript" src="javascripts/libs/jquery-1.7.2.min.js"></script>
    <script type="text/javascript" src="javascripts/detect.js"></script>
    <script type="text/javascript" src="javascripts/bg.js"></script>
    <!-- <script type="text/javascript" src="javascripts/extensionmessage.js"></script> -->
    <!--<script type="text/javascript" src="javascripts/background.js"></script>-->
    <script type="text/javascript" src="javascripts/data-collection.js"></script>
    <script type="text/javascript" src="javascripts/libs/ga.js"></script>
<body class="bg_page">
<script type="text/javascript" src="javascripts/cga.js"></script>
<img src="" alt="Test Image" id="test_image"/>
<img src="" alt="Temp Image" id="temp_image"/>
<canvas id="tempCanvas"></canvas>
<video id="desktop-video" autoplay></video>
<canvas id="video-canvas"></canvas>

Does this help?

Big thanks.

Modified by cor-el

more options

It's definitely not uBlock Origin.

The script names are too bland to point me to something specific -- detect.js, bg.js, background.js, data-collection.js, ga.js [possibly Google Analytics?], cga.js -- but the page contains an embedded video player placeholder, which I guess could be consistent with several of your scripts.

Often a script name in the source viewer will be a blue link you can click. Does that work? You could look at detect.js or some of the others and see whether they contain any clues about what extension they belong to. Basically, you're looking for a title, author, copyright notice, or any signs of what it is, toward the top of the anticipated jumble of code.

more options

Okay, that page is from Awesome Screenshot Plus. No idea why it shows up in history.

Edit: Adding screenshot.

Modified by jscher2000

more options

Isn't (techo) life interesting!!

Thanks for identifying the add-on concerned, Jscher2000 and I understand that there is no identified reason why it's behaved this way. I deleted the item from the History, closed Firefox and reopened it. Hey presto, no History items.

Unless one or other of you good guys have another track to follow, I think that during the day I'll keep an eye on History and see whether something reappears at a particular point.

I'm also conscious that the-edmeister mentioned the nuclear approach of refreshing Firefox and I'll keep that in mind.

I'll also make an update posting as that all unrolls.

Big thanks!!!  :-)

more options

A thought: as you've identified the item as from Awesome Screen Shot perhaps I should delete it and reinstall.

Could be that it's now "carrying" something and a delete/reinstall would give a clean installation?

more options

I wonder whether it shows up in history after you use the extension the first time? Or when it updates? I don't think it anything to worry about because we're talking about a page internal to your own system.

On the other hand, the add-on uses Google Analytics to track something, so that would be worth pondering... why is it doing that?

more options

Appreciate the thinking, Jscher2000.

Some "testing" shows that the History does not reappear until the computer is closed, rebooted and a new browser window opened. Within the one session, once the item is deleted from History it does not return, even if Awsome Screen Shot is used.

Your comment about Google Analytics and tracking caught my attention. Reducing/eliminating tracking in order to improve privacy for online purchases, banking, etc., is what my switch to Firefox private mode (as default) is all about .....

If one of you good people have no other suggestions, my next step will be to do a Refresh of Firefox - probably Monday as the rest of the weekend is spoken for. I've captured lists of Add-ons and Extensions and will add them back one by one, checking History each time. Fairly labourious but seems to be the way to go ...... :-)

I'll post an update ......

more options

There was a new version of Awesome Screenshot Plus made for Firefox 48.0 Plus versions. And it's been updated twice already since it was made compatible with 48+. I wonder it that is one of the new "WebExtensions" for Firefox?

And here - - mentions the Chrome extension and "working out issues with Google regarding our Awesome Screenshot extension on the Chrome Store." I wonder if Diigo has made a cross-browser compatible extension, that works with Chrome and Firefox? Which is one of the goals that Mozilla has for WebExtensions in Firefox.


I think you should contact Diigo about this issue with their Firefox extension, especially if this problem is new in Firefox 48.0 & the ASP 3.0.# versions; and it wasn't in an earlier version of their Awesome Screenshot Plus extension versions 2.4.11 and older, for Firefox 47 and older. A fix for Firefox is going to have to come from Diigo and it might be something that Diigo needs to make Mozilla aware of, too.

WebExtensions is a new era for Firefox extension development and this might be a Bug on the add-on developer side and / or something that Mozilla needs to work on or at least make note of it in Mozilla Developer Network documentation. And something that needs to be addressed when "converting" a WebExtension for the different browser platforms.

One last thing; I wonder how or if Private Browsing is involved? Could ASP be creating a "temporary" HTML file due to not having the "Cache" available for "storage" of a temporary HTML file, and it ends up in History instead "disappearing" from RAM as Firefox is closed??

My suggestion is to not use Private Browsing and see if that History item is not created. IOW, make sure that it is related to Private Browsing, which it sure sounds like to me.

In closing, jscher2000 is a lot sharper on this than I am, and you are probably too. But whatever this turns out to be I feel that Diigo needs to be made aware of this "glitch"; and Diigo should contact Mozilla directly if it turns out to be a problem with Mozilla implementation of WebExtensions in Firefox.

Oh, one last thing - I have seen mention of "moz-extensions" in the Location Bar autocomplete drop-down (and probably appears in History, too) in at least one support thread in this fora within the week to 10 days, but I can't find it via a search of support threads. My "search-fu" sucks, so I'm not surprised that I couldn't find it.


more options

Ed the-edmeister!

Food for action you've given me. Thanks for it.

I'll do the non-private browser test and also the Firefox refresh and then pass it all on to Diigo. Seems I have stuff to keep me occupied - and in active brain mode - for a while.

As I mentioned in an earlier post, I'll keep you advised.

more options

Thanks for the quick response. Good luck with getting this resolved or getting action towards a resolution.


  1. 1
  2. 2