By proper update I mean trying to ensure that the old files are removed and the new files are applied. I felt like maybe you had tried to update, but I'm not certain. Not everyone understands the process and they find ways to mess stuff up. There are 2 approaches to updating the mod; I recommend the first unless problems continue.
1) The low effort way. Delete the old AricsExpansion mod folder in AppData and add newest mod folder. Run the game and apply the mod.
2) The highly effective way. Rename "Strive" folder in AppData and extract a new set of downloaded game files. Run game to main menu and quit in order to generate a new" Strive" folder, add newest AricsExpansion mod folders, and apply the mod.
edit: in expansion, on line 279, there's a typo, it says : daysumilked instead of daysuNmilked, not sure if that's the problem, testing now
Edit 2:it appears, that in the save, the variable "Restrained" is False for some slaves, and "none" for others, I think the error is due to false being a boolean, and the code is looking for a string
now that that is done, after i fixed that, im getting these: this is from going to the next day twice, the first time was with the cattle being locked in, the next they weren't, a few of the errors is because there isn't a restraintype or stress_mod in the save file (i think), but the Invalid operands errors are not