Unity-Technologies/UnityCsReference · error · ArgumentNullException

The object to add cannot be null.

Error message

The object to add cannot be null.

What it means

Thrown by BuildProfile.AddComponent<T>(T objectToAdd) when the supplied objectToAdd is null. This is a standard null-guard using ArgumentNullException with the parameter name. Because T is constrained to UnityEngine.Object (which can have a 'fake null' state), the check catches both true null and destroyed-but-referenced Unity objects.

Source

Thrown at Editor/Mono/BuildProfile/BuildProfile.API.cs:108

                }
            }

            return null;
        }

        /// <summary>
        /// Adds a given component to the build profile. If the component is not an asset in
        /// the project, it will be added as a sub-asset to the build profile.
        /// </summary>
        /// <typeparam name="T">Component type</typeparam>
        /// <param name="objectToAdd"></param>
        /// <exception cref="ArgumentNullException">Thrown when objectToAdd is null.</exception>
        /// <exception cref="ArgumentException">Thrown if adding a sub-asset of an existing component type.</exception>
        public void AddComponent<T>(T objectToAdd) where T : UnityEngine.Object
        {
            if (objectToAdd == null)
            {
                throw new ArgumentNullException(nameof(objectToAdd), "The object to add cannot be null.");
            }

            // Don't allow duplicates
            var found = GetComponent<T>();
            if (found != null)
            {
                throw new ArgumentException($"The component {typeof(T).Name} already exists in the build profile {name}.");
            }

            var assetPath = AssetDatabase.GetAssetPath(objectToAdd);
            if (string.IsNullOrEmpty(assetPath))
            {
                objectToAdd.hideFlags |= HideFlags.HideInHierarchy;
                AssetDatabase.AddObjectToAsset(objectToAdd, this);
                return;
            }

            // TODO: Future API will support build profile components as reference.

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Null-check objectToAdd before calling AddComponent and handle the missing-object case explicitly.
2. Ensure the object is actually created (e.g. ScriptableObject.CreateInstance returned non-null) before passing it in.
3. Investigate why the reference is null — it often indicates an earlier creation or lookup that silently failed.

Example fix

// before
profile.AddComponent(someField); // someField is null

// after
if (someField != null)
    profile.AddComponent(someField);
else
    Debug.LogError("Cannot add a null component to the build profile.");

if (objectToAdd == null) throw new System.ArgumentNullException(nameof(objectToAdd));

static bool IsValid(UnityEngine.Object o) => o != null; // catches fake-null too

When it happens

Trigger: Passing a null reference, a not-yet-assigned field, or a reference to an already-destroyed UnityEngine.Object to AddComponent. Also triggered when a ScriptableObject.CreateInstance call returned null due to an invalid type.

Common situations: Uninitialized fields passed into AddComponent; using an object that was destroyed by DestroyImmediate or AssetDatabase operations; deserialization producing a null; logic that assumes a creation step succeeded without checking its return value.

Related errors

• The object to remove cannot be null.
• Platform GUID {platformGuid} is not a valid Unity build plat
• Active build profile is null.
• guid
• prefabInstance

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/498b1cd900041321. Report an issue: GitHub.