Too-long file name: which iOS app owns it? I have an iPhone that I back up to a Mac (via iTunes), and the backup is failing. The error shown in iTunes is useless, but the console shows this:

Jan  6 20:53:58 aron-mbp.local AppleMobileBackup[71561]: ERROR: Backup message response: 101 stat error: File name too long (63) at path "/var/mobile/Containers/Data/Application/C3147DA8-A001-4A6C-BF8D-971DC2678722/Documents/iCache/pinterest.com/nevadamagazine/dataimage/pngbase64iVBORw0KGgoAAAAN....nT+soTf+" (MBErrorDomain/101)

(I've snipped quite a lot of characters out of the file name, as it is, in fact, extremely long.)

So, it looks like some app has created this huge-named file, which is stuffing up the backup process because iOS can't stat it and barfs.

I figure, deleting the offending app should delete the file and fix the problem. But: which app is it? All I have to go on is the unique ID or whatever it's called, C3147DA8-A001-4A6C-BF8D-971DC2678722. Is there a way to determine which app this corresponds to? I'm happy to dig through the ipa files if necessary.

(I've tried deleting the Pinterest app, given the presence of 'pinterest.com' in the path, with no luck. I've shotgunned a few others, again with no luck.)

This is iOS 8.1.2.
The GUID (globally unique identifier) you see is randomly generated by iOS at the time of installation or update, and not related to the app in any way - in fact, it even changes between updates and reinstalls. Previously, apps were kept at /var/mobile/Applications/&lt;GUID&gt;/blah.app with Documents, Library and tmp alongside it in its sandbox, however now in iOS 8 that's changed so /var/mobile/Containers/Bundle/Application/&lt;GUID&gt;/blah.app contains the app and /var/mobile/Containers/Data/Application/&lt;some other GUID&gt; contains the data. Unfortunately, the data and bundle GUIDs don't match, so that's made it a lot harder to track down.

On a jailbroken device, you could use the iFile app from Cydia to navigate through the file system to the offending file and delete it. I would recommend you also check the Library/Preferences folder so you can see the bundle identifier of the app, which should help you determine the offending app, so you can report this issue to the developer. It's worth noting that the developer is using the Documents folder to store caches, which is meant for, well, documents. They should be using Library/Caches, which isn't backed up by iTunes.

You could alternatively use iCleaner Pro (I haven't used it before so I can't give you specific instructions).

Another method if you don't have a/don't want to jailbreak would be to download iFunBox (note for Windows users: download the classic version) and look through the application list manually until you happen to find Documents/iCache/.... Right click the offending file and choose Delete.

A last-ditch method is to fill up your disk with data, which triggers iOS to start clearing app caches to make some room.