Dwarf Fortress Bug Tracker - Dwarf Fortress
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0010840Dwarf FortressDwarf Mode -- Trapspublic2018-07-17 07:582018-07-17 11:07
Windows10, 64 bit
0010840: two pressure plates cannot be linked to the same door; "Could not find path."
Two pressure plates cannot be linked to the same door. Upon linking the second one, the job is suspended with the error "Could not find path."
Build a door and two pressure plates. Link the first pressure plate to the door; it works. Link the second pressure plate to the door; "Urist McMechanic cancels Link a Building to Trigger: Could not find path. The dwarves suspended a linkage from Pressure Plate."
"Could not find path" is the same error message that arises when attempting to link a forbidden door to any trigger, which makes a kind of sense; because the door is forbidden, the dwarves are not only barred from pathing through it but also from pathing *to* it, so they believe they cannot access the forbidden door to install the linking mechanism. It could be that since doors are no longer dwarf-operable once they are linked to a mechanism, the game internally treats them kind of like "forbidden" and that prevents dwarves from installing additional mechanisms.

On the other hand, this problem does not arise when linking two levers to the same door, even though that also makes the door non-manually-operable, so it's not a door-specific issue. There is also no problem linking two pressure plates to the same bridge, so it's not a pressure-plate-specific issue either; there seems to be something about the specific combination of doors and pressure plates that prevents multiple linkages.
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Issue History
2018-07-17 07:58taledenNew Issue
2018-07-17 08:03taledenNote Added: 0038608
2018-07-17 11:07lethosorAssigned To => lethosor
2018-07-17 11:07lethosorStatusnew => acknowledged

2018-07-17 08:03   
Perhaps also of interest, while searching for information on this issue I came across these comments from 3 years ago referring to the same problem:

https://www.reddit.com/r/dwarffortress/comments/2lly4c/levers_and_pressure_plates_a_guide_by_mechanixm/ [^]

"Note: I had to remove and then rebuild my Door that I had used in the previous example here. You can't have two different Pressure Plates hooked up to a Door apparently. I'm not sure how many items will have this same problem, but it does not affect Bridges."

"Incidentally, it IS possible to hook up multiple pressure plates to one door. They just need to be able to be on the door's tile in order to hook mechanisms to it, but when the door is operated via pressure plate they can't open the door themselves. So hook a lever to the door BEFORE you hook your pressure plates. Then pull the lever, door is open, dwarves can hook the door to whatever else your heart desires."

This doesn't seem to explain why a door can be linked to two levers without having to use one of them to open the door first, but it does suggest perhaps an easy solution: change the "link building to trigger" job to be doable from an adjacent tile (as in building/removing constructions) and not only the target tile.