Although your tag says ArcGIS Desktop.. perhaps you could explain what you are doing that results in that error message.
ArcMap? ArcGIS Pro?
Do you have a screen grab? to show what specifically you are referring to?
I am using ArgMap 10.6 version.
I created .mxd with GDB file after load that file from .Net desktop application.
Map loaded but i try to add marker it will throw exception as previously i said.