In Edge, it's not possible to create or edit a content item.

Prereq.: Use Microsoft Edge browser on Windows 10.

Steps for edit:
1. Log in as admin on http://devdemo.ez.no/ez.
2. Go to Content / Content structure.
3. From Content tree open any of the Top stories.
4. Click Edit.
Actual: Application hangs on spinning wheel, in console error occurs "Argument not optional".
Expected: It's possible to enter edit mode w/o errors.

Steps for create:
1. Log in as admin on http://devdemo.ez.no/ez.
2. Go to Content / Content structure.
3. Click Create.
4. Choose e.g. Folder.
Actual: Application hangs on spinning wheel, in console error occurs "Argument not optional".
Expected: It's possible to enter edit mode w/o errors.

Remarks: Occurs with IE 11 on Windows 7 also.