When I start from the command line I get errors as below, along with a bunch more in a similar vein. I have a few hundred torrents, but I don't see a significant improvement if I delete a bunch of them.
I'm on 4.1.9.1, on an up to date version of Mint Cinnamon. I don't see this kind of error with any other applications.
Happy to test any suggestions.
qbittorrent
qt5ct: using qt5ct plugin
qt5ct: D-Bus global menu: no
qt5ct: D-Bus system tray: yes
qt5ct: custom style sheet is disabled
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/24/qbittorrent-tray.svg', because: Too many open files
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/24/qbittorrent-tray.svg', because: Too many open files
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/16/qbittorrent-tray.svg', because: Too many open files
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/16/qbittorrent-tray.svg', because: Too many open files
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/22/qbittorrent-tray.svg', because: Too many open files
qt.svg: Cannot open file '/usr/share/icons/Mint-Y/panel/22/qbittorrent-tray.svg', because: Too many open files
QProcessPrivate::createPipe: Cannot create pipe 0x56069528e768: Too many open files
QProcessPrivate::createPipe: Cannot create pipe 0x56069528e768: Too many open files
QProcessPrivate::createPipe: Cannot create pipe 0x56069528e768: Too many open files
(qbittorrent:10947): Gtk-WARNING **: 09:47:23.782: Error loading theme icon 'dialog-information' for stock: Error opening file /usr/share/icons/Mint-Y/status/48/dialog-information.png: Too many open files
(qbittorrent:10947): Gtk-WARNING **: 09:47:23.816: Error loading theme icon 'gtk-ok' for stock: Error opening file /usr/share/icons/Mint-Y/actions/16/gtk-ok.svg: Too many open files
** (qbittorrent:10947): WARNING **: 09:47:23.825: Pixbuf theme: Cannot load pixmap file /usr/share/themes/Mint-Y-Teal/gtk-2.0/assets/notebook.png: Failed to open file '/usr/share/themes/Mint-Y-Teal/gtk-2.0/assets/notebook.png': Too many open files
(qbittorrent:10947): GdkPixbuf-CRITICAL **: 09:47:23.825: gdk_pixbuf_get_width: assertion 'GDK_IS_PIXBUF (pixbuf)' failed
(qbittorrent:10947): GdkPixbuf-CRITICAL **: 09:47:23.825: gdk_pixbuf_get_height: assertion 'GDK_IS_PIXBUF (pixbuf)' failed
** (qbittorrent:10947): WARNING **: 09:47:23.825: Invalid borders specified for theme pixmap:
/usr/share/themes/Mint-Y-Teal/gtk-2.0/assets/notebook.png, borders don't fit within the image