Some print drivers and applications add new back ends to CUPS, if you are using checkBox™ or logSheet™ you will need to link them.

X2 Print Accounting logSheet and checkBox automatically add new back end transports as un-tracked. To change them to tracked they must be symbolically linked to ../bin/x2pa. The back end transports for logSheet and checkBox are located in /usr/local/x2pa/cups/backend.

If you have backends in /usr/local/x2pa/cups/backend/ that are old or linked to the wrong place you can remove them. However, if you are not familiar enough with unix to do this without instruction, you probably shouldn't try.