I download a file geodatabase from an outside source. For some reason when the file creator does a join the field names get really long so I attempt to shorten them back the original field name after I use the copy features tool to import them into my sde. I was using the Alter Fields tool but it has been failing. I keep getting an error that certain fields cannot be changed because they are a custom sde type column.

I would understand this if I was actually altering one of these types of fields but I am not. These are the fields I am trying to alter by removing the SDE_SDE_Parcels_

I just tried to do this manually since the tool was not working correctly. Any idea on how to get around this issue?