I noticed my game was being really laggy, so I saved and restarted it. When I reopened it, I was met with this:
The error looks like it might relate to a ladder, or the task of building one. Perhaps load the save and try deleting ladders, if you have any that you built. For ladders created by Hearthlings for building, I am not sure how you could fix.
That was my first thought. I used to console and the destroy command and wiped out all the ladders, reloaded, and the problem was still there. I canceled the building they were making and reloaded, still a ladder error 
Bump because I did it again, and used the destroy command to destroy every ladder. The hearthlings were idle and had no orders. Once the ladders were gone, I reloaded, I got the same error. I think it may have been caused by me having placed a ladder, then putting a road under it. Before the hearthlings built the road, it was a floating ladder.
EDIT: Different save than previous.
Hello all!
So Im running into an issue with Engine errors followed by < 10 FPS, and high memory usage (~97%), which is severely lagging my PC. This has happened on three occasions and I’ve had to delete/create a new town each time. I read on the forums that it is common with multiple story buildings or mining too large of an area. However, the first time I had nothing queued because I was letting my citizens move items to my stockpile. The second time, only a stone path was being built (about 2 x 20). This last time, I have 3 single homes and 2 stone walls (1 x 20 + 1 x 25) are in queue.
Here is my screenshot:
My specs:
I HAD the cook mod on, but I removed it after the first town ran into this issue.
oh no its the nil ladders.
This is an active bug somewhere else that I started, and it does ruin saves. Every time that save is loaded you will get that error. It seems to happen when ladders have a block removed from beneath them, or the engine forgets how to ladder
oh joy!
Well, at least it’s an issue that has been seen by others… and here I thought I was special!
I tried to place a fence anywhere on the map and it gave me this error over and over again!!
This is a weird bug that appears at random times, ruining the game 
By the way, what’s with the big stones in your screenshot? 
I kind of miss the scale there. Are they floating?
I got this bug with trying to build the castle that I designed…
If I let the game run long enough pretty soon I can’t click anything in game (i can select something initially but it doesn’t show what I selected, then later that even stops happening). I watched the game memory usage and it seems to just keep increasing in a linear rate until it maxes out all 16 gigs of RAM that I have installed and system manager says the game is using >25% of the CPU.
Also, don’t know if the game is supposed to have two .exe open but after this error I always have to go into system manager and kill one processes that wasn’t shut down after closing the game (by X’ing out, since I can’t even get the menu to come up with the Esc key)
350c759e-24b8-11e5-a87e-bc5ff43a636f
No, they are giant stones I made with my awesome hacks. xD JK they are floating
Every time I load my save this error appears :
develop-2494 (x64)
...tonehearth/services/server/build/ladder_builder.luac:11: attempt to index local 'ladder' (a nil value)
stack traceback:
radiant/modules/events.luac:68: in function <radiant/modules/events.luac:65>
...tonehearth/services/server/build/ladder_builder.luac:11: in function 'self'
radiant/modules/events.luac:80: in function <radiant/modules/events.luac:78>
[C]: in function 'xpcall'
radiant/modules/events.luac:78: in function <radiant/modules/events.luac:70>
It’s in relation with ladders, of course, which I use a lot. But I don’t really know how and when the error appears the first time.
EDIT : Another one just appears, but still don’t know how…
develop-2494 (x64)
...tonehearth/services/server/build/ladder_builder.luac:11: attempt to index local 'ladder' (a nil value)
stack traceback:
radiant/modules/events.luac:68: in function <radiant/modules/events.luac:65>
...tonehearth/services/server/build/ladder_builder.luac:11: in function 'self'
radiant/modules/events.luac:80: in function <radiant/modules/events.luac:78>
[C]: in function 'xpcall'
radiant/modules/events.luac:78: in function <radiant/modules/events.luac:70>
develop-2494 (x64)
stonehearth/components/water/water_component.luac:83: assertion failed!
stack traceback:
radiant/modules/common.luac:32: in function <radiant/modules/common.luac:32>
[C]: in function 'assert'
stonehearth/components/water/water_component.luac:83: in function '_grow_region'
stonehearth/components/water/water_component.luac:57: in function '_add_water'
...rth/services/server/hydrology/hydrology_service.luac:175: in function 'add_water'
...rth/services/server/hydrology/hydrology_service.luac:240: in function '_process_water_queue'
...rth/services/server/hydrology/hydrology_service.luac:237: in function '_on_tick'
...rth/services/server/hydrology/hydrology_service.luac:13: in function '_fn'
radiant/controllers/timer_controller.luac:28: in function 'fire'
radiant/controllers/time_tracker_controller.luac:9: in function <radiant/controllers/time_tracker_controller.luac:9>
[C]: in function 'xpcall'
radiant/controllers/time_tracker_controller.luac:9: in function 'set_now'
...earth/services/server/calendar/calendar_service.luac:112: in function 'fn'
radiant/modules/events.luac:79: in function <radiant/modules/events.luac:78>
[C]: in function 'xpcall'
radiant/modules/events.luac:78: in function 'trigger'
radiant/modules/events.luac:97: in function '_update'
radiant/server.luac:19: in function <radiant/server.luac:17>