“Blueprint could not be loaded because it derives from an invalid class. Check to make sure the parent class for this blueprint hasn’t been removed! Do you want to continue (it can crash the editor)?”
-I can’t open blueprint unless i click yes.
-I have tried almost everything on on internet that says “fixes this problem” but nothing
I’ve started to get this error after i did change a file name and open my editor . Now it’s driving me crazy for almost 2 days. Any suggestion will be appreciated.
You could try couple things depending on your situation.
If you only renamed the object, change it back to what it was previously. that should fix it (you probably already tried that)
Check the Auto save folder to see if the version of the file before you renamed it exists there. You can find it in [ProjectName]/Saved/Autosaves/Game/…
If you found the non renamed file, just copy and paste it back where it’s supposed to go. I would also copy and place the child class too, if it’s there.
One thing to note is that the asset name probably has “_Auto1” or something at the end, make sure to remove that from the name before opening the editor.
Also never change file names outside the editor, instead rename files from the content browser.
When you rename in the editor, it’ll automatically create redirectors to point to the new file name.
Hey thanks for answer. I have found some files on that adress but i did not get what they ment
these was the files i’ve found.
Btw _Advanced BP’s has missing parent problem
What was the parent class of Advanced BP before the problem?
The Abstract one
Copy the Abstract file to wherever it was in the content folder before you renamed it.
Rename it to remove “_Auto3” ( AC_BuildingSystem_Abstract_Auto3.uasset → AC_BuildingSystem_Abstract.uasset ). Then try opening the project.
Didn’t work 
Oh, sorry. Hopefully someone else here knows another way.
Btw I have tried reparinting and it made engine crash with this error:
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000060
UnrealEditor_Core
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_KismetCompiler
UnrealEditor_Kismet
UnrealEditor_Kismet
UnrealEditor_Kismet
UnrealEditor_UnrealEd
UnrealEditor_Kismet
UnrealEditor_Kismet
UnrealEditor_Kismet
UnrealEditor_Kismet
UnrealEditor_ClassViewer
UnrealEditor_ClassViewer
UnrealEditor_ClassViewer
UnrealEditor_ClassViewer
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
user32
user32
UnrealEditor_ApplicationCore
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
kernel32
ntdll
