Created attachment 136689 [details] Sample .nii.gz file. The file is the gzipped file of .nii, which can be directly opened by ITK-SNAP without unzipping to .nii. SUMMARY Recently I cannot open .nii.gz files with dolphin by single left click (this is the default option when opening files instead of double left click), showing Invalid Protocol. The specified software to open this kind of file is ITK-SNAP, where I once assigned it in right click - Open with - Other Application... - ITK-SNAP with Remember all files of type checked. I only encounter this kind of problem recently while this works before, and assigning again has no effect. Strangely, there's no problem when I access files on Network (like sftp on the server). And right click the file and choose the first option Open with ITK-SNAP the file is normally opened in ITK-SNAP without Protocol Invalid alert. Other kinds of files are able to open normally with the assigned software. STEPS TO REPRODUCE 1. Assign .nii.gz files to ITK-SNAP (once). 2. Open a local or remote (sftp) .nii.gz file. 3. Open a local .nii.gz file by right-click and choose Open with ITK-SNAP. OBSERVED RESULT Displays Invalid Protocol when left clicking the local file. Normal when right clicking and choose the default opening option. Normal when opening the network (sftp) file in ITK-SNAP. EXPECTED RESULT SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.10.23.1-lts/5.21.2-1 x64 (available in About System) KDE Plasma Version: 5.21.2-1 KDE Frameworks Version: 5.80.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION I'm using Kvantum 0.19.0