Problem statement
What I have tried: Moving the root hair bone of a skeleton to inspect it.
What actually happened: Spine crashed.
Reproducing the problem
Duplicate a skeleton and build a new rig on it (keeping only the image slots from the original)
Bind multiple bones to meshes on the duplicate skeleton
Move the root hair bone of the original skeleton — crash occurred
Note: The original skeleton was created in Spine 3.8.99 and imported into 4.3.90-beta. This did not crash initially. After binding multiple bones to meshes on the duplicate skeleton, I moved the root hair bone of the original and the crash occurred. The root hair bone had multiple nested transform constraints.
Editor information
Spine Editor version: 4.3.90-beta Professional
Spine Launcher 4.3.01
Esoteric Software LLC (C) 2013-2025 | http://esotericsoftware.com
Windows 10 Pro amd64 10.0
NVIDIA Corporation, NVIDIA GeForce RTX 3060 Ti/PCIe/SSE2, 4.6.0 NVIDIA 596.36
Starting: Spine 4.3.90-beta Professional
Spine 4.3.90-beta Professional
Using customized hotkeys: hotkeys-1.txt
Started.
OpenAL 1.1, Default audio device
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
Automatic backup complete.
ERROR: An unexpected error has occurred:
[npe] Cannot read field "_" because "<parameter1>._" is null
at s.uxu._(_:220)
at s.uxu.p(_:174)
at s.hdI.Z(_:754)
at s.INz.I(_:509)
at s.WPU.D(_:184)
at s.INz.D(_:615)
at s.iVv._(_:313)
at s.bPJ._(_:78)
at s.WPU._(_:97)
at s.INz._(_:200)
at s.bNk.D(_:53)
at s.RFq.D(_:206)
at s.rid.D(_:78)
at s.RFq.D(_:180)
at s.lPt8.D(_:127)
at s.lPt8.D(_:127)
at s.rIF.D(_:104)
at s.VFD._(_:46)
at s.rIF._(_:35)
at s.RMf.run(_:251)
<events>
