I was just doing a few things on my farm before heading to the winter market, when a model spawned out of one of my fruit trees and started heading toward the southern exit of the farm. It was Chaem specifically who I am not married to and I've never seen her on my farm before.
Reproduction Steps: I don't know? I'm not sure what caused this at all. **ETA I was between the trees around 20:40 when she popped up under one of them and emerged.
Repro Rate: Only happened the one time. Will update if it does.
Game Platform: Steam
Game Version: v1.1b-1237
Input Mode: Keyboard and mouse
#NPC spawned on my farm?
elfin elm
urban kelp
Chaem wants to see your farm! 
But yeah… she’s not supposed to be there! 😆
@elfin elm, could you let us know the in-game date and time when this issue occurred? Also, if you are still on Winter Festival week, does Chaem appear there again on the other days?
Thanks for bringing this to our attention!
elfin elm
Sorry! I added the time in an edit, but it was Winter 20. I haven't seen her be anywhere she shouldn't (besides just now lol). Just the normal places, but I'll keep an eye out for her in case it happens again and update if it does!
urban kelp
Sorry! I added the time in an edit, but it was Winter 20. I haven't seen her be ...
Got it! Yes, please let us know if you see her on your farm again—thank you! 
Additionally, could you also share your Backup folder as a ZIP file? It’s located in the same place as the DailySave file.
urban kelp
Well received! One more thing—could you describe your in-game activities on that day, if you still remember?
Also, did you interact with Chaem before this happened, such as asking her to hang out or seeing her Heart Event?
elfin elm
I didn't talk to anyone. I just did a few things around the farm like move around some of the automation I'm working on and then I went to the mine for osmium and put it in the furnace. It was right after I put it in the furnace that I was walking down toward my shed to see if anything needed to be moved when Chaem popped up and scared the crap out of me. I didn't recognize her at first because I was startled, so I had to chase her down to talk to her. It actually took a few tries for her to speak to me.
urban kelp
I didn't talk to *anyone*. I just did a few things around the farm like move aro...
I’ll add that to the notes—thank you so much, languid!
We’ll look into this and keep an eye out to see if anyone else experiences the same issue. 
elfin elm
It happened again! Winter 28 around 10:00, and this time I couldn't speak to them at all. I only saw them come from the direction of the trees along the path. He's walking up toward the eastern exit of the farm. Same as last time, spoken only to my spouse and cat and rotated some things around the farm. Haven't even left the farm yet, so haven't seen anyone else.
**Ammendment: He's just standing up by the pond. I've managed to speak to him, but he's not making any moves to leave my farm now.
urban kelp
It happened again! Winter 28 around 10:00, and this time I couldn't speak to the...
Oh! We've received similar reports about Walter from other players as well. However, we haven’t been able to replicate this issue on our end.
@elfin elm, did you play through Winter 27 and then continue straight into Winter 28 without exit or restarting the game?
If so, do you happen to have a video of what happened, or could you describe your in-game activities on Winter 27 in detail?
Thanks for your help! 
elfin elm
Yeah, I had played for a few days before it happened. I believe I had been mining again on Winter 27. Just working on my automation and caring for my animals before going to the mine. It also crashed not too terribly long after Walter popped up, but I'm uncertain if it was related.