Ok, that would probably be something new, though I have my suspicions that the cause is related to switching back and forth between the versions. Using a farmhand and a farm manager on my old save does not produce any errors for me. The fact that it does not occur when the farm manager is not present simply means that when the farm does nothing there is no problem. Several of the mod's data structures have been updated as well as the code for updating those data structures, so I cannot completely discount the possibility that there is bad code.
It's quite possible that simply re-triggering the version update for the save file may fix it. This can be accomplished by editing the save file with any text editor and changing the value after "expansionversion" to 1.5 . Edit: I should also mention that it is recommended that you make a backup of the save file before editing it, as mistakes can be hard to fix.
If that does not fix it, then in order to correctly diagnose the problem, you will need to either:
- Install the Debug mod. This will not fix the problem but it changes the behavior of the executable when bugs occur and provides error messages. Posting those error messages should tell me what needs to be fixed.
- Share your save file, Discord is an easy place to drop the file for sharing, otherwise you would need a file sharing service.