I am trying to add a new column to a freshly created list. The list was created through the UI.
Now, when I try to add a new column to it through the UI, I get the following error:
Field name already exists.
The name used for this field is already used by another field in the list. Select another name and try again.
If i try to add via the Designer, I get the following error:
Could not save te field changes to the server.
I can create a site column. However, if I try to add it to the list, or its content types, I get the same errors.
I have checked, and there are no conflicting field names. I get the error for any name, even random character sequences.
What can I do to solve this?