NEW PHYSICS REGISTRATION RULES FOR STUDENTS TAKING PHYS OVER THE SUMMER
If you are taking a summer Physics course, you will not be able to register for a subsequent course during advanced registration. You would have to have completed the prerequisite course before asking for an override, meaning that you likely will not be able to register for a UIUC PHYS course until August.

Due to the high volume of students on the PHYS prerequisite checklist at the beginning of each semester, the physics department has decided that students taking summer courses at other institutions will need to submit their prereq override request after they have successfully completed the class. They can submit their override request along with a snapshot of their final grade to the campus portal here Submit Undergraduate Petition - My.Physics Portal - U of I (illinois.edu)