SUMMARY Having a file in a fuse mount point (in my case: mergerfs, an union filesystem) confuses dolphin in the detection of that file type and can't open it by simply pressing "enter" for example on existing setup: Changing to the mergerfs pool folder, then create a file in terminal like "echo asdf>xyz". Go with dolphin to that folder. Pressing "enter" in dolphin to open xyz gives unknown file type (application/octet-stream) Right-click, open with, gives simple text file (text/plain) So there seems to be a confusion in detection. Choosing "remember association" on the "open with", does not work in the sense that next time pressing enter to open xyz gives the same problem. "xdg-mime query filetype xyz" does list the type as text/plain. "xdg-open xyz" opens file even if there's a error : "kf.service.services: KApplicationTrader: mimeType "x-scheme-handler/file" not found". This error might be another unrelated bug. All files, regardless if they work or not in dolphin, give the above error but open anyway with xdg-open. The "file" tool returns "xyz: ASCII text", so it also detects it correctly. To replicate outside of existing setup, I did the following: -create virtual machine with 2 drives -install o.s. then mergerfs (it was version 2.33.3. Tried 2.40.2 in real machine, it doesn't change a thing) -created the folder for the mount point of the mergerfs pool (for ex: /media/user/mergerfspool) -created the folder for the mount point of second drive (for ex: /media/user/drive2) -change ownership of those mount points to me (user) -change /etc/fstab to represent all mounts and mergerfs. ----for Mergerfs it can be (without quotes) "/user:/media/user/drive2 /media/user/mergerfspool fuse.mergerfs defaults,func.create=rand,moveonenospc=true,allow_other,use_ino,fsname=mergerFS 0 0" -create the file: " echo asdf>/media/user/mergerfspool/xyz " result with dolphin: -if xyz is opened directly from the branch (real underling folder) or is outside mergerfs pool, it always works. -if xyz is opened from the mergerfs pool, it will not open and instead give the above behavior. As a side notes: -file manager "Krusader" has no problem either way. -I also tested with another fuse mount, with sshfs. Same problem. -started happening when upgraded to plasma version 6.0.3 and all that came with it like "KDE Gear 24.02.1" Operating System: KDE neon 6.0 KDE Plasma Version: 6.0.3 KDE Frameworks Version: 6.0.0 Qt Version: 6.6.2 Kernel Version: 6.5.0-26-generic (64-bit) Graphics Platform: X11 System Version: -CF