Comment # 5 on bug 1165359 from Mindaugas Baranauskas

After updating kio and kio-core packages from your repository, I closed Firefox
and started it again. I tried to download file into newly created
sub-sub-sub-sub-sub-directory, but kmozillahelper still crashed.

However this time Dr. Konqi was not started and backtrace was not rised by it.
I only see in command line:

> firefox
kf5.kio.core: Invalid URL: QUrl("MYFILE.png")
kf5.kio.core: Invalid URL: QUrl("MYFILE.png")
KCrash: Application 'kmozillahelper' crashing...
*** Error in `/usr/lib/mozilla/kmozillahelper': realloc(): invalid old size:
0x000055d6c929bcd0 ***
Unable to start Dr. Konqi
Re-raising signal for core dump handling.

Maybe I need restart whole KDE Plasma session?