I created a new domain called 'Object'. I tried to assign it to a field. It did not work: it simply would not appear in the domain field of the field properties dialog after I clicked it. I then tried to delete this domain. This also did not work. I created a new domain called 'Obj' and this performed correctly. Please advise. Possibly, ArcCatalog/Map/etc should inform users automatically when they try to name a domain 'Object' that it will not work. Please advise me if it will ever be possible to delete this domain or if I will have to recreate the whole file geodatabase. Version: ArcGIS Desktop 10.5.1.
My guess is Object is one of those words you should avoid in terms of naming things. Falls into the same category as Shape, ShapeLength, etc....
I had a similar though. This problem, however, should not occur because Esri should design their software such that it will warn users not to use these domain names. Only a company with a monopoly would do this, or simply a poor software development company.
I just tested it on a newly created File geodatabase and worked fine for me. I can create a domain named "Object", assign it to a field and later delete it too. I was using Desktop 10.4.x.
So it is not an Esri limitation or restriction..
I also tried in ArcGIS Pro 2.3 and can add a domain called Object to a file gdb and apply the domain to a field.
When I try to delete the domain before removing it from the field first, I get this error:
Ahhh, that is a good error message. So I'll remove it from use first, then see if I can delete it.