My lubunutu is installed in a virtual machine. Whenever I try to open the file manager from taskbar icon nothing happens. If I try to open the file manager from desktop options I get this message
Failed to execute child process "lxsession-default" (No such file or
directory)
BTW my desktop options also changed. Previously clicking right mouse button would let me access options such as change background etc. now they are missing and replaced with open file manager, multimedia etc. My desktop background is now blank.
Best Answer
I had the same issue. What resolve the issue for me was to open LXQT settings then Desktop. Click on advanced tab and uncheck "show menus provided by windows managers when desktop is clicked" under Window Manager.
Lubuntu 19.10