Cannot detach data item from notebook

Hello NotebookEnjoyer 

What you're experiencing is how Fabric Notebooks are designed to behave!

In a Fabric notebook, only ONE Warehouse can be the “primary” Warehouse. The first attached Warehouse becomes permanently bound. That primary Warehouse can never be removed. Any additional Warehouses are secondary and can be removed. You can try this with the other Warehouse you have attached. 

It seems the one you tried to remove is the first Warehouse you attached to your notebook. 

Fabric internally assigns the first Warehouse as Notebook SQL execution context. So it follows this rule

First Warehouse = permanent

Subsequent Warehouses = optional

If you want to “change” the primary Warehouse:

1. Create a new notebook
2. Attach the desired Warehouse first
3. Copy notebook content
4. Delete the old notebook

This is the only supported way to change the primary Warehouse.

Hi, same problem, the solution that i found was deleting all sources from the OneLake source and then adding them again.