I reproduced the following behavior often: 1. Mount a sshfs filesystem in a home folders direct sub folder. 2. Open a folder contained in this filesystem. 3. Disconnect the sshfs filesystem providing server by disconnect the network interface. 4. The open dolphin window (which was opened in step 2) don not react the mouse input anymore. If I open a new dolphin window, the application in normally useable, except if I open the home folder (sub folders are not the folder in which the sshfs was mounted are not affected), no contents are showed, the progressbar in the right down corner are active. If I navigate the the folder in which the sshfs is mounted, the current window do not react the mouse inputs, too. After a few minutes all affected windows react to mouse inputs again.
This is a known issue, but the bug is not in Dolphin. See also https://bugs.kde.org/show_bug.cgi?id=75324#c20 and following comments. For example, if I run dolphin in gdb and I reproduce the freeze, backtrace says: Thread 1 "dolphin" received signal SIGINT, Interrupt. 0x00007fffef326e55 in _xstat () from /usr/lib/libc.so.6 (gdb) bt #0 0x00007fffef326e55 in _xstat () from /usr/lib/libc.so.6 #1 0x00007ffff00a3770 in ?? () from /usr/lib/libQt5Core.so.5 #2 0x00007ffff003bfa8 in QFileInfo::exists(QString const&) () from /usr/lib/libQt5Core.so.5 #3 0x00007ffff5eedcd0 in KFileItemActions::addServiceActionsTo (this=0x7fffffffb610, mainMenu=0xfe2c50) at /home/elvis/dev/kde/src/kio/src/widgets/kfileitemactions.cpp:282 #4 0x00007ffff7b11edf in DolphinContextMenu::addServiceActions (this=0xfe2c50, fileItemActions=...) at /home/elvis/dev/kde/src/dolphin/src/dolphincontextmenu.cpp:487 #5 0x00007ffff7b10c5f in DolphinContextMenu::openViewportContextMenu (this=0xfe2c50) at /home/elvis/dev/kde/src/dolphin/src/dolphincontextmenu.cpp:358 which means the hang is in the low-level filesystem calls... Workaround: don't use sshfs + Dolphin, use the sftp ioslave instead (type sftp://user@server in the Dolphin URL bar). You many need to install the kio-extras package if you don't have it already.
Created attachment 103062 [details] Minimal Qt application that also hangs I can reproduce the freeze also with the minimal Qt application attached, so this is definitely not a Dolphin issue. The root cause is probably: https://github.com/libfuse/sshfs/issues/3
*** Bug 367759 has been marked as a duplicate of this bug. ***