This article describes how to resolve "Error: property 'value' can't be empty value (null, 0, false, 0.0.0.0, "", ...)" when editing a signature in App Control.
After migrating settings from a Gen6 device to a Gen7 device, sometimes when editing the signatures in App Control, it results in  "Error: property 'value' can't be empty value (null, 0, false, 0.0.0.0, "", ...)". Hence the signature cannot be edited.
       
If you are not able to edit some signatures :



If you are not able to edit all the signatures :

CAUTION:This will Reset all the configurations of App Control and set all the values to default. If you want to avoid resetting the App Control Settings, then change each signature manually as shows above that has "undefined" value.