Haven't played in a while, since probably 0.15.20 or so.
Updated to 0.16.x.
Started the game.
Immediate popup after the logo screen, on top of the patch notes dialog, that says:
"Data error
Failed to load the player data file. Campaign
progress might be lost."
I closed Factorio and restarted and the dialog didn't appear a second time, so perhaps this is something that only happens the very first time you upgrade to 0.16.
