Having been a loyal Linux user for MANY years (almost 15) LMDE Update Pack 6 just did an amazing thing - it installed perfectly and EVERYTHING WORKED on re-boot.
There were about a half-dozen errors on the terminal as the upgrade proceeded, and I was prepared for a long night, but on re-boot - SUCCESS!!! Everything, including my Nvidia graphics card, all desktop settings, and all application customisation was intact and so far everything is just PERFECTLY NORMAL!!!!!
This has never happened before, and I have been a Debian (and on old machines a Vector Linux) user all these years.
Kudos guys - GREAT JOB! I knew it could be done. And to think I was feeling griped because updates were so slow coming. Never again. Your Quality Assurance is spot on.