a unlocked cell on a protected sheet, when use the toolbar buttons to make the text bold, underlined, etc in the unlocked cell, got: "The cell that you are trying to change is protected and locked."

The error message is misleading, since the cell is unlocked.

Excel's behavior: not allow user to change text bold, underlined etc.. with a unlocked cell on a protected sheet, excel doesn't have popup any error message, it only disabled those buttons