Problem
I recently started using Fortinet FortiGate firewalls for the first time. After creating a VLAN interface by mistake I was a little confused about how I could remove it. After selecting the VLAN interface the Delete button at the top of the screen was greyed out with no clear explanation as to why.
Solution
I personally think this is one thing, especially if you are new to FortiGate firewalls that is not as clear as it could be in the GUI. It would be better if the button was active and just gave you a pointer why you can’t delete it just yet.
The reason the delete option is not available is that there is another configuration referencing it.
You need to remove this other configuration(s) before you can delete the interface. This is confusing if you create an interface by mistake and want to delete it as FortiGate has automatically created some additional configuration referencing your new interface, blocking deletion.
The easiest way to find configuration referencing your interface is to click on the number in the “Ref” Column
In the popup that appears you will need to check and delete the referencing configuration.
After removing all of the referencing configurations the Delete button will be available.
Learning more
If you are new to FortiGate firewalls, as I recently was. Or you just want to improve your skills Udemy has some great courses for a reasonable one-time fee. I am also a big fan of Pluralsight
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