I’ve noticed for a while that changing the type of a component declared in C++ will effectively ‘break’ any blueprints that inherit from it. Specifically, the details panel for that component will always show up blank, which makes it nearly impossible to work with. E.g:
I’ve tried a lot of solutions to get around this problem, from renaming variables to reloading the blueprint, but none have consistently worked. The only real solution I’ve found is to remake the blueprint from scratch and painstakingly reassign all of the detail panels for every component. For more complex blueprints, this is really not ideal and has forced me to heavily rely on data assets to ensure that no data gets lost.
There are many times when changing the type of a component is unavoidable, so I was wondering if anyone had found a better solution to this issue?
After further testing, I’ve found that this only happens when moving ‘sideways’ or ‘backwards’ through an inheritance hierarchy. But moving ‘downwards’, like from a scene component to a sphere component, this issue doesn’t occur. This doesn’t solve the problem, but it may give a better idea of what the problem is.
When you change the C++ type of a UPROPERTY component, the serialized Blueprint data no longer matches the reflected type, so the Blueprint ends up holding stale serialized data and the Details panel goes blank.
A few important points / mitigations that usually help:
Changing component types in-place is not supported. UE does not migrate serialized data between component classes, even if they’re closely related.
Renaming the variable alone usually isn’t enough because the underlying serialized subobject still exists in the BP asset.
The least painful workflow is:
Add a new component property with the new type (new name).
Compile, open the BP, reassign settings.
Remove the old component property afterward.
If you must reuse the same name, sometimes this works (not guaranteed):
Close the editor
Rename the property in C++
Recompile
Reopen editor
Rename it back to the original name
For critical components that may change type, prefer:
A common base component class
Or composition via child components created in BP instead of hard C++ ownership
Your approach of moving important data into Data Assets is actually the correct long-term safety net and is what Epic recommends internally.
Bottom line: there’s no reliable automatic fix today. Avoid changing component types on inherited Blueprints when possible, and when unavoidable, migrate via a new property rather than in place
Yeah I figured this might be the case. Thanks for the response! It sucks that there isn’t really a 100% fix, but at least there are some workarounds to make it less frustrating to deal with.
