Unable to save level with different name

Development Programming & Scripting
1

hello, when i try to save my level with a different name i get this

"Can’t save …/…/…/…/…/…/Perforce_Workspace/x0003Project_A/Content/maps/Map_N3.umap: Graph is linked to object(s) in external map.
External Object(s):
Map_N2_C
CurveFloat_4
CurveFloat_2
CurveFloat_3
CurveFloat_0
…

Try to find the chain of references to that object (may take some time)?"

there is no map “Map_N2_C”
and i dont know where are these:
CurveFloat_4
CurveFloat_2
CurveFloat_3
CurveFloat_0

even when i delete the event graph and all the content from the worldoutliner
the error consists

2

kind of a solution is, to set the level as “abstract class” save it as different name
and uncheck “abstract class”

but it would be nice to know whats the issue