I upgraded from W7 to W10 last month. Is there any way to tell the exact date? I'm having some horrible problems due to a missing user file. If I have a backup of one program that was made before I upgraded, I can just reinstall the program and all is well. If I don't, per the software designer, I've just lost 3 years of work because Dropbox can't find the missing pathways. I just can't remember when December 2015 I finally upgraded.