arcpy.RemoveFeatureClassFromTopology_management error - possible bug?

[Kathleen_Crombez]

I am running a tool in arcpy to remove a feature class from topology...

arcpy.RemoveFeatureClassFromTopology_management(topo, fc)

here is the error message...

File "T:\ArcSDE\Fabric\FabricQC.py", line 274, in buildTopo

    arcpy.RemoveFeatureClassFromTopology_management(topo, fc)
File "C:\Program Files (x86)\ArcGIS\Desktop10.5\ArcPy\arcpy\management.py", line 18028, in RemoveFeatureClassFromTopology
    raise e
ExecuteError: ERROR 999999: Error executing function.
Cannot register as versioned on this database.
Cannot register as versioned on this database.
Failed to execute (RemoveFeatureClassFromTopology).

umm... what does this tool have to do with registering as versioned?

Does anyone have any experience with this error from this tool? How do I get around it?

I am using ArcDesktop version 10.5.1