I am tracking an issue (r. 32534132) where, under very hard to reproduce circumstances, NSURLSession will call your URLSession:downloadTask:didFinishDownloadingToURL: delegate method with a file URL that’s completely bogus, and this will result in an error like the one you’re seeing here. In that case, however, the actual URL is very different from the one you posted. Instead of being inside your app’s container: /var/mobile/ Containers/Data/Application/ ContainerUUID/ Library/Caches/com.apple.nsurlsessiond/Downloads/ YourBundleID/ CFNetworkDownload_Random.tmp it’s relative to the root of the file system. /var/mobile/ Library/Caches/com.apple.nsurlsessiond/Downloads/ YourBundleID/ CFNetworkDownload_Random.tmp I am encountering this problem? Any updates?

Based from response, the file is temporarily downloaded in file:///var/mobile/Library/Caches/com.apple.nsurlsessiond/Downloads/xxxxx/CFNetworkDownload_qb9hwG.tmp I cannot copy this file to my download location since I am encountering an error: (NSError) error = 0x00000002818928e0 Error Domain=NSCocoaErrorDomain Code=257 "The file" CFNetworkDownload_qb9hwG.tmp "could not be opened because you do not have permission to view it." UserInfo = {NSFilePath = /var/mobile/Library/Caches/com.apple.nsurlsessiond/Downloads/xxxxx/CFNetworkDownload_qb9hwG.tmp, NSUnderlyingError = 0x2818927c0 {Error Domain = NSPOSIXErrorDomain Code = 1 "Operation not permitted"}} I am assuming the temporary file should be saved in my App Folder. Additional info: My app is registered with the Microsoft Identity platform

Again, how reproducible is it for you? Always, never succeeded in downloading files in background session.