When clicking on "instance option" in Service portal nothing happens.The glide modal window for "instance options" never appears. Instead browser console error is show below in developer tools:
SyntaxError: Unexpected token u in JSON at position 0
at JSON.parse (<anonymous>)
at removeExtraFields (widget-options-config.js:45:23)
at massageView (widget-options-config.js:41:20)
Out dated "forms" widget
The widget responsible for building the "instance option" is called "Widget options config".
On line 32 of the server script in widget "Widget options config". We can see that a modal window is being built based on the "form" widget. If the "form" widget is out of date. You will receive the error "Unexpected token u in JSON at position 0".
Use a out of box instance to ensure that the "form" sp_widget record is up-to-date. If not, reimport the up-to-date XML file into your instance.