What causes a feature dataset to suddenly become unversioned? I was editing a versioned feature class adding attachments. I needed to make an edit to an individual feature and I kept getting an error message that said I couldnt change a table without being in an edit session. Turns out that the dataset lost its versioning and I had to reregister as versioned. Is there something causing this to happen? I also discovered that multiple other datasets in the same SDE geodatabase also had to be registered as versioned again. I also ran MXD Doctor just to see if the MXD was causing an issue. As of now, everything appears to be working again but I want to know why this happened in the first place.
A feature dataset itself is not versioned or unversioned -- the feature classes inside of the feature dataset are the ones that get versioned and unversioned. So if there is any new data added to a Feature Dataset or if there is any Feature Class within the dataset which is not versioned, then the Feature Dataset will also show up as not versioned.
But why am I allowed to add attachments but not edit the feature class? I guess that's because the table is on its own with a relationship class. The whole hierarchy thing is just confusing. If I have to register the feature classes at the feature dataset level how can you say that the dataset is not versioned? I don't recall making any changes that would have caused this but it is hard to say when it happened. This is something I find extremely frustrating about SDE. In order to add anything new I have to stop my services, I also have to stop my services to remove the locks to register anything as versioned. I didn't have to deal with that when I was using file geodatabases for my services. It may be important to note that the main reason I switched to SDE was for feature services and the attachments feature. I am currently the only user so I don't have to worry about multiple editors. The reason I have everything versioned is for editing purposes only and of course if in the future I add users, I would already have things set up that way.