Why You’re Seeing This Error
This error means the Blueprint is based on a parent class that no longer exists or is unavailable in the current project build.
In UE5, this often happens when:
- You delete or rename a C++ class that a Blueprint was derived from
- A plugin that defined the parent class has been disabled or removed
- The Blueprint was created in another project and the required class doesn’t exist in this one
- The class is marked as
abstract,deprecated, or can’t be used for instancing
💥 Example Error Message
Blueprint could not be loaded because it derives from an invalid class
🛠️ Common Blueprint Scenario
[BP_EnemyCharacter] was originally based on [C++EnemyBaseCharacter]
C++EnemyBaseCharacter was deleted or renamed.
Now BP_EnemyCharacter fails to load.
✅ How to Fix It in UE5 – Step-by-Step
✔️ 1. Restore the Missing Parent Class
If it was a C++ class or plugin:
- Rebuild or re-add the class to your project
- Re-enable the plugin it came from
- Recompile the project
✔️ 2. Reparent the Blueprint (If Possible)
If the Blueprint still opens in the editor, do this:
Open BP_YourBlueprint
→ File → Reparent Blueprint
→ Choose a valid class like Character or Actor
→ Compile and Save
✔️ 3. Replace with a Valid Class (If It’s Totally Broken)
If you can’t open it:
- Create a new Blueprint from a valid base class
- Manually migrate functionality (if any)
- Delete or archive the corrupted Blueprint
✔️ 4. Avoid Renaming C++ Base Classes Without a Plan
When renaming a class used by Blueprints:
- Update all derived Blueprints
- Recompile the project before launching the editor
- Consider using redirectors or keeping a stub class temporarily
✅ Summary: How to Fix “Blueprint Could Not Be Loaded Because It Derives from an Invalid Class”
| Cause | Fix |
|---|---|
| Parent class was deleted or renamed | Re-add or recompile the missing class |
| Plugin was disabled or missing | Re-enable the plugin or restore the class definition |
| Blueprint can’t find valid base | Reparent the Blueprint manually |
| Class marked abstract/deprecated | Use a different base class |
