OnTriggerStay2D stopped working after upgrading to Unity 5

As the title says OnTriggerStay2D stops working after we upgraded to Unity 5.

That’s simply not true. May be a bug in your version of Unity, but most likely something else going on. Works fine in my scenes and I also did a new test scene with triggers, colliders and rigidbodies and their 2D version to confirm that it works as described in the documentation. Have you tested it in an empty scene with simple objects? Maybe you changed some IsTrigger parameter or used a wrong script.

So it turns out before we used to have RigidBody2d only on one of the colliders, but in Unity 5 that didn’t work.

The solution was to make sure both of the objects that want trigger must have RigidBody2D componenet.