arcpy.AlterField() Error 99999 - fail to rename all fields with their alias?

[JohannesBierer]

Hello,

I try to rename the fields of a feature class with their alias name, but I get an error message ERROR 99999.

I use notebook in ArcGIS PRo 2.9.3

Any ideas why?

inFc = "A4_Moorkulisse_2022"
fields = arcpy.ListFields(inFc)

for f in fields:
   
    print (f.name + " - " + f.aliasName)
    
    if f.aliasName in ("OBJECTID", "SHAPE"):
        
        continue
    
    else:
        arcpy.management.AlterField(inFc, f.name, f.aliasName, f.aliasName)

print output:

A4_Moorkulisse_2022.OBJECTID - OBJECTID

A4_Moorkulisse_2022.SHAPE - SHAPE

A4_Moorkulisse_2022.A3_Moorkulisse_2022_A2_Moorkulisse_2022_A1_Moorkulisse_2022_SP_R - Ref_Prozent

ExecuteError: ERROR 999999: Beim Werkzeug ist ein unerwarteter Fehler aufgetreten. Wenden Sie sich an den technischen Support von Esri (http://esriurl.com/support), und ziehen Sie die Fehlerhilfe zu Rate, die Informationen zu möglichen Lösungen oder Problemumgehungen enthält.
Fehler beim Ausführen von (AlterField).

[Anonymous User · Accepted solution]

You can't have spaces or dashes in the field name.

 legal field names 

[JohannesBierer]

Ah Ok, thank you for your answer.

But it wasn't me who puts points in the field name, it is caused throught several arcpy.managment.AddJoin and then copy features processes .... so I don't know how to avoid the points?

[JohannesBierer]

If I use this it seems to work, convert to string:

arcpy.management.AlterField(inFc, str(f.name), str(f.aliasName), str(f.aliasName))

 Thank you JeffK for the hint with the legal field names ...