Ok, here's what I think is happening.

• If you download Firefox and install it, and then try to install it again, you'll get the simpler 'An item named "Firefox.app" already exists in this location' message. That's fine and expected.
• If you download a Firefox version, e.g. 46.0.1, then let it update itself to 47.0.1. Download the new version (47.0.1) and try and install it over the top, then you'll see the 'A newer item named "Firefox.app" already exists in this location.

The reason this second case is happening is because the local version of Firefox has updated itself.

When it updates it only gets a smaller snippet of differences from the server. It will update the appropriate files locally, and they'll get the timestamp when that update happened.

So when you then try and download and install over the top with the newer version, it will see different timestamps and notify you about it.

I short, I don't think there's an issue here, I think this is just how the system works.

The issue has nothing to do with my clock it is set to the right time zone and time.

Their is 2 people who have the same problem. I would appreciate if you could state if you have the same Mac OS yosemite.

This problem occurs also in Tor Browser 6.03 which uses firefox.

This issue occurs when the Mac is online ( wifi )

mace2, I didn't say this was a problem with your clock. It is a in-built Mac warning mechanism, that is functioning as expected.

I can easily reproduce it here.

Please re-read my previous comment. I think that explains the difference in the two dialogs you've seen. They are effectively both warning dialogs.

The only reason you see the "A newer item..." message sometimes is that Firefox has updated itself on the hard drive - it has obtained a new version and downloaded it to the hard drive to the place you installed the original version.

This update mechanism works differently to when you download Firefox and install it manually. As a result, Mac can see it as "a newer item", that's not an issue, that's just how it works.

Standard8 I don't think you are reading my posts. I am currently running version 48.0 the latest version and if I reinstall the "Firefox 48.0.dmg" sha512 value: 41d8d17fce2a4af94f32c21d9e0d2c3985961cb46f463d2d40e7a0c83140af1c84386e29012beadfe8759d82bf69fa54c8c761fa2e60628d3e63f93831b2be3f

It will state a "a newer version of Firefox.app already exists" This is not possible as 48 is the latest available version for Aug-16-2016.

Hi mace2, the earlier screen shot said there is "a newer item" not there is "a newer version." A newer item indicates that the timestamp of the existing file is newer than the timestamp of the file you want to replace. It could be the same version.

Either way, I think it's still suspicious that the timestamp updated. At least on Windows it would be suspicious, I don't know the details of how Firefox works on Mac.

Update: Sept-2016 This problem only occurs when Firefox is open. when I use another browser and reinstall Firefox I get the expected message of a item called Fiorefox already exiist. This suggest the change is some how communicating through an active Firefox.

Update: Sept-2016 48.01 Does not recognize a newer version 48.02 is available for the Mac when about Firefox is clicked. It just says Firefox is up to date

mace2 said

Update: Sept-2016 48.01 Does not recognize a newer version 48.02 is available for the Mac when about Firefox is clicked. It just says Firefox is up to date

Firefox 48.0.2 was mainly a fix for Windows version as Mac and Linux users do not really need it anyways.

https://www.mozilla.org/firefox/48.0.2/releasenotes/

Version 48.02 exhibits the same problem.

Hi mace2, I've just been digging through the code a bit.

What is happening is that approximately every 24 hours Firefox does an update check to see if there's a new version. When it does that, it creates (and removes) a temporary file in the Firefox.app/Contents/MacOS directory. The purpose of this is to check if it has permissions to do the update or not. This happens regardless of if there is an update actually present on the server.

From Firefox 49 (should be released next week), I believe the temporary file will no longer be written due to other changes in the update system - (non-admins will be able to update Firefox if they can provide admin details).

Hence with the temporary file no longer being written, I believe that the application directory won't be changed, unless there has actually been an update.

Standard8 I dont think your explanation fits. 1 I have been attempting to find any changes in the Firefox files but could not find anything as of yet. If you could name the file I can verify.

2) Firefox with no other applciation running appears to communicate via TLS (secure communications) to other sites even though no URL has been requested and all other communications applications on my Mac are not runnning.

Hi mace2, regarding your #2, please see whether that is covered here: How to stop Firefox from making automatic connections.

Thanks for the suggestion jscher2000 however I have none of the possible applications or home screens enabled. I have Firefox set to sent no diagnostic information and I have shut down RTC and OpenH264 codec is disabled. I did have ad-block plus enabled.

The only suggestion that applies is Malware. Even though no URL address was entered and after validating the sha hash for firefox the operating system is clearing identifying Firefox performing the communications.

Hi mace2.

The temporary file that I spoke about is only created for a few milliseconds, it is then removed again. Without debugging Firefox to pause it at the right time, the only evidence of this is that the timestamp on the Firefox.app/Contents/MacOS directory has changed.

Firefox 49 was released yesterday, and that should no longer be writing to the directory.

For #2 I think the only way we can help you further is if we know what servers Firefox is contacting - there's various things it could be.

This issue has been corrected in version 49