Thanks! The issue is that your mesh is self-intersecting:
That plays havoc on the math needed to do auto weighting. Apologies it doesn't give a better error message.
To fix it you can move the vertices so the mesh doesn't self-intersect, then auto weights will work.
You will then find that changing the weights makes the vertices move. This is because the bones have been moved from where they were when the bones were bound to the mesh. When that happens, the various bones want the vertex in different positions, so when weights change the vertex position changes.
To fix that if you click the Update button in the weights view it will update the bone bindings using the current bone and vertex locations. Now adjusting the weights will not change the vertex positions.
This is quite a tricky part of mesh weights, so don't worry too much if you don't fully understand it at this time. To learn more about it check this part of the docs:
https://esotericsoftware.com/spine-weights#Update-bindings
