The -a means to run on all mounted filesystems, so the error could be from any of them. Try running it on each filesystem and see which one is causing the message ( which likely isn't your ntfs partition ).
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to util-linux in Ubuntu. https://bugs.launchpad.net/bugs/1516702 Title: fstrim on 30 GB ntfs partition says 16 EiB (18446744073709551615 bytes) trimmed Status in util-linux package in Ubuntu: Incomplete Bug description: fstrim on 30 GB ntfs partition says 16 EiB (18446744073709551615 bytes) trimmed SSD: Plextor M5pro 128GB ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: util-linux 2.26.2-6ubuntu3 ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3 Uname: Linux 4.2.0-18-generic x86_64 ApportVersion: 2.19.1-0ubuntu4 Architecture: amd64 CurrentDesktop: Unity Date: Mon Nov 16 17:41:03 2015 InstallationDate: Installed on 2015-10-22 (25 days ago) InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021) SourcePackage: util-linux UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1516702/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
