I ran the delete field tool deliberately on a geopackage to see what happens and I got an error message. This did not surprise me as I have read in the help that I cannot drop fields in a geopackage featureclass. Whilst that is something I would like ESRI to resolve what I was surprised is that there is no documentation on error code 002557 as you can see below.
![DuncanHornby_0-1648469538014.png DuncanHornby_0-1648469538014.png](https://community.esri.com/t5/image/serverpage/image-id/37455iAA4D88A8FD89388E/image-size/large?v=v2&px=999)