On a iOS 13.5.1 device I am running in to issues where nsurlsessiond is terminated due to the below exception. This seems to be random for both download and upload tasks I have submitted to a background session. I am submitting the tasks from a FileProvider extension. This is happening while the Files app is still in the foreground. My FileProvider extension receives Error Domain=NSURLErrorDomain Code=-997 "Lost connection to background transfer service" when nsurlsessiond is terminated. Is this a know bug that has been fixed in later iOS versions? From console: default 14:15:53.446034+0100 nsurlsessiond Task <DD63D88A-B440-4430-8648-00CCCE262BCC>.<9> suspending default 14:15:53.446094+0100 nsurlsessiond Task <DD63D88A-B440-4430-8648-00CCCE262BCC>.<9> resumeTaskWithIdentifier, props <private> default 14:15:53.446139+0100 nsurlsessiond Task <DD63D88A-B440-4430-8648-00CCCE262BCC>.<9> resuming, QOS(0x15) debug 14:15:53.446199+0100 nsurlsessiond Task <DD63D88A-B440-4430-8648-00CCCE262BCC>.<9> Updating configuration on daemon default 14:15:53.446228+0100 nsurlsessiond Create activity <nw_activity [F58BE911-7C48-4F00-BB0C-9B65CF36EE4A] (lightweight)> debug 14:15:53.446249+0100 nsurlsessiond [Telemetry]: Assiging taskMetrics on the daemon side default 14:15:53.446362+0100 nsurlsessiond Task <DD63D88A-B440-4430-8648-00CCCE262BCC>.<9> resuming default 14:15:53.446413+0100 nsurlsessiond (501) setup voucher for background work with account:151417C1-9686-4AE7-A375-EB278C1692F2 default 14:15:53.450537+0100 nsurlsessiond (501) Succesful&#9;voucher adoption for persona:151417C1-9686-4AE7-A375-EB278C1692F2 debug 14:15:53.450670+0100 nsurlsessiond <NSProgress 0x11bd2bff0> Unpublishing 8163C890-7312-4601-B3A5-B410CBE71B17 default 14:15:53.450783+0100 nsurlsessiond * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[0x11bd2bff0 publish]: this instance of NSProgress has already been published and can't be published again.' First throw call stack: (0x1a22e5794 0x1a2007bcc 0x1a27de850 0x102ace8b4 0x1a1f5dc8c 0x1a1fab524 0x1a1f578a4 0x1a1f58294 0x1a1f6178c 0x1a1ffcb74 0x1a1fff740)