Created attachment 110649 [details] Partition Manager error on desacticating Luks partition On Mint 18.3 KDE: I have a hard drive with gpt partition table and a single encrypted luks partition. Works: - Mount/decrypt using dolphin file manager - Mount/decrypt encrypted partition from KDE Partition Manager Not working: - unmount/deactivate in KDE Partition Manager - Even if mounted using KDE Partition Manger - Provide useful error message detail Duplicate: 1. Mount an encrypted luks partition 2. In KDE Partition Manager right click on partition and choose "Desacticate" Result: Error message: "The file system on partition /deb/sb1 could not be unmounted" Clicking on detail: "pre></pre>" Note: AFAIK nothing was using the partition. Had no problem with unmounting in dolphin.
Can you try with the newer Partition Manager, e.g. by using live cd with some other distro. Some parts of unmount code were also rewritten after 1.2.1, so it might be that this bug was fixed a long time ago. I definitely haven't seen anything like that recently.
Works for me on Plasma 5.12 and KDE Applications 17.12.2. Unfortunately, Linux Mint uses ancient versions of our and everybody else's software. Please see https://community.kde.org/Get_Involved/Bug_Reporting#Step_2:_Make_sure_it_hasn.27t_already_been_fixed Please re-open if you still have the issue with more recent software.