Printer "Filter failed"

I encountered the same problem. To track back its origin I looked into /var/log/cups/error_log

In my case, I discovered that the problem was caused by icc profiles used by ghostscript. I had the following error:

Started filter pstops (PID 26489)    
./base/gsicc_manage.c:1244: gsicc_open_search(): Could not find default_gray.icc    
./base/gsicc_manage.c:2261: gsicc_init_iccmanager(): cannot find default icc profile   
./base/gsicc_manage.c:1244: gsicc_open_search(): Could not find default_rgb.icc    
./base/gsicc_manage.c:2025: gsicc_set_device_profile(): cannot find device profile   
**** Unable to open the initial device, quitting.   

So what worked out for me has been to manually remove the icc profiles and then re-install libgs9-common (following this link: Broken ghostscript configuration):

sudo rmdir /usr/share/ghostscript/9.25/iccprofiles   
sudo apt-get install --reinstall libgs9-common   

Hope this helps