With Vault Professional 2015, a user can sometimes see this message when promoting an item.
(The operation failed for the following reasons. Restricted Items/Files: Item #: Suspension, Restriction: Cannot insert an item into itself)
This can happen if the parent and child BOM components have the same Part Number and the user is using the default numbering scheme that is based on property mapping.
They can get out of this situation by fixing the Part Number or by unchecking check box for “Auto-select first duplicate item” (under Tools > Options) and then repeating the Assign Item command again.
Thanks Anil Chintamaneni for sharing this issue with us!