stride3d/stride · error · Exception

RigidBody must be valid

Error message

RigidBody must be valid

What it means

The single-body CreateHingeConstraint overload builds a hinge between one rigid body and the world. rigidBodyA anchors the hinge and is required; passing null would dereference into the native Bullet constructor, so the API throws a validation exception first.

Solutions

1. Assign/resolve the RigidbodyComponent before creating the hinge constraint.
2. Validate the reference with a null check and fail early with a clear message.
3. Move hinge creation to Start/scene-loaded time when components are guaranteed initialized.

Example fix

// before
var hinge = Simulation.CreateHingeConstraint(rigidBodyA, pivot, axis); // rigidBodyA null
// after
var hinge = Simulation.CreateHingeConstraint(rigidBodyA ?? Entity.Get<RigidbodyComponent>(), pivot, axis);

if (rigidBodyA == null) throw new InvalidOperationException("rigidBodyA must be assigned before creating hinge");

bool IsValidBody(RigidbodyComponent b) => b != null && b.Simulation != null;

try { var h = Simulation.CreateHingeConstraint(a, pivot, axis); } catch (Exception ex) when (ex.Message == "RigidBody must be valid") { /* fix body reference */ }

When it happens

Trigger: Calling Simulation.CreateHingeConstraint(null, pivotInA, axisInA) — usually because a component lookup or field assignment returned null.

Common situations: Hinge setup in a script whose rigid body reference was never assigned in the editor or found via entity.Get<RigidbodyComponent>() returning null.

Related errors

• Both RigidBodies must be valid
• must be valid
• Both RigidBodies must be on the same simulation
• ArgumentNullException: descriptions
• ArgumentNullException: paramName

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/4d58f10cf93aa9e5. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Physics/Simulation.cs:667

            if (rigidBodyA == null || rigidBodyB == null) throw new Exception("Both RigidBodies must be valid");
            return CreateConstraintInternal(type, rigidBodyA, frameA, rigidBodyB, frameB, useReferenceFrameA);
        }

        /// <summary>
        /// Creates a hinge constraint using a specialized constructor.
        /// </summary>
        /// <param name="rigidBodyA">The rigid body a.</param>
        /// <param name="pivotInA">Pivot point in body a.</param>
        /// <param name="axisInA">Axis in body a.</param>
        /// <param name="useReferenceFrameA">if set to <c>true</c> [use reference frame a].</param>
        /// <exception cref="System.Exception">
        /// Cannot perform this action when the physics engine is set to CollisionsOnly
        /// or
        /// RigidBody must be valid
        /// </exception>
        public static HingeConstraint CreateHingeConstraint(RigidbodyComponent rigidBodyA, Vector3 pivotInA, Vector3 axisInA, bool useReferenceFrameA = false)
        {
            if (rigidBodyA == null) throw new Exception("RigidBody must be valid");
            return CreateHingeConstraintInternal(rigidBodyA, null, pivotInA, default, axisInA, default, useReferenceFrameA);
        }

        /// <summary>
        /// Creates a hinge constraint using a specialized constructor.
        /// </summary>
        /// <param name="rigidBodyA">The rigid body a.</param>
        /// <param name="pivotInA">Pivot point in body a.</param>
        /// <param name="axisInA">Axis in body a.</param>
        /// <param name="rigidBodyB">The rigid body b.</param>
        /// <param name="pivotInB">Pivot point in body b.</param>
        /// <param name="axisInB">Axis in body b.</param>
        /// <param name="useReferenceFrameA">if set to <c>true</c> [use reference frame a].</param>
        /// <exception cref="System.Exception">
        /// Cannot perform this action when the physics engine is set to CollisionsOnly
        /// or
        /// Both RigidBodies must be valid
        /// </exception>

View on GitHub (pinned to 96fad776d2)