Gentlemen, could it be the same issue we are aware of for Windows 8? Since both Windows 8 and Windows Phone 8 share same core the issue could be same here. The known fact is: Windows keeps ALL the unpacked versions of APPX files installed ever in %ProgramFiles%\WindowsApps folder. That's a hidden folder with the ACL owned by the special TrustedInstaller SID, but if you look at it under an elevated process such as Windows Explorer, or, easier, FAR Manager, you'll see the folder holds multiple copies of same apps:
Moreover, uninstalling apps does NOT clean the app folders, they are kept there in the %ProgramFiles%\WindowsApps folder. Could it be the same issue with Windows Phone, I wonder?
So it could be
, Windows Phone keeps all unpacked XAP files there, in the phone's memory and marks it as 'Other' (because they aren't really apps, they are SFXes, only unpacked or deflated). All in all, what seems to happen when you install an app or update it:
1. Windows stores its XAP to phone's memory and keeps it for the sake of recovery
2. XAP are also unpacked into their program folder
3. When you update an app, it downloads a new XAP, stores it, and unpacks to its own program folder, keeping both the old program folder and its corresponding XAP intact. That's each and every time you update an app.
4. When you uninstall an app, Windows unregisters its contracts in Windows registry, removes some XAML files that represent the entry point for the app, but that's it, it does not remove any other content, neither it removes any assemblies.
So what I suggest for the time being (that all is my assumption I don't know if any piece of it could be true by any chance):
1. Try installing/updating apps from a SD card ONLY (when your phone supports it).
So instead of tapping Install/Update, do the following:
1. Go to windowsphone.com and download a XAP from there.
2. Save the downloaded XAP somewhere on your PC (it is not possible for some reason to download right to the SD card).
3. Copy the downloaded XAP to the SD card (you can copy to the root of the card, or you can create a folder on the SD card, like .\Apps, and place the XAP there).
4. Wait for some time (I don't know how much, that's all mystic when Windows does a refresh to scan the SD card) and open the Market app.
5. Now you'll see the SD Card category added in the end of the list of standard apps, music, etc. categories.
6. Open that category and you'll see (or you won't when Windows did not a lookup for the XAPs on your media yet) the copied XAP archives there; install from there by setting a check box next to apps).
I wonder if it could help anyhow, but who knows.
On top of that, on Windows 8, every app has its own isolated folder where it keeps its work files, like Mail keeps every attachment you've ever received, IE keeps its own cache which is separate from the cache used by the Internet Explorer Desktop. That's a lot to learn about Windows and it seems like it has many features that haven't yet been finished. Say you have defeated DLL hell problem, well welcome, %systemroot%\WinSxS and %ProgramFiles%\WindowsApps that both keep a gazillion of different versions of assemblies used by .NET applications. Hope MSFT is aware of this and is working on it.
How do you like this on Windows 8:
That's the versioning history of all versions of ADBE Flash ever been installed to my system. While it only proves for the fact that ADBE is probably the worst software maker known to date, it gets you puzzled why would Windows need to keep all the versions when I can't revert to them?
Who would say there's nothing like that in Windows Phone 8 provided that both are the same operating system
I would say, I'd tested apps on a virtual emulation software before installing them to your physical phone, but I won't do that because you can't get real-life experience working with phone app on a PC.
What I did not get from reading this thread: does the software reset help here?
In my view it should help, as it removes every user app, but does it actually help?