Am tying to enable "Allow Dynamic Inserts" for "ITEM CATEGORIES" code under "Item Categories" Flexfield system is throwing me an error message "Field is protected against update".
Please check whether you have frozen the flexfield or not.
After freezing the form will not allow you to change the checkbox.
Unfreeze the FF, select Allow dynamic inserts and compile the FF..
If the issue is something else, please let us know, whether the same happens for all Flexfields or not ..