I updated both of my iPhones to iOS 9.0.1. Now the personal hotspot feature will not function on either iPhone.
This is a major disaster for me: here it is nearly midnight, and I planned to leave at 5:00 AM tomorrow for a 10 day trip. I rely heavily on internet via the Personal Hotspot feature. I even carry two phones just in case one fails.
I've rebooted both phones, swapped cables, etc. All software including iTunes is up to date (version 126.96.36.199). No go.
I'm furious. Apple Core Rot in OS X has been bad enough. But when traveling, I have to take care of my business needs every day. Remote areas I visit have cell service here and there, but do not have WiFi hotspots without hours of round-trip driving. It's a disaster. I don’t know what to do at this point; I have commitments and cannot abort my trip. Yet I need internet access while there.
These days, the Apple gestalt seems to be “entertainment and leisure” and it shows in product quality for getting useful work done—Apple shovels out new releases on a schedule (not for value or quality reasons), while adding new bugs at a rapid pace. Maturity and judgment at Apple seem to be sadly lacking in terms of ensuring that products upon which professionals rely maintain their integrity.
SOLUTION found, about 1 AM
Consider that if I had not pre-tested before leaving, I’d have had no way to download the fix! Chicken and egg problem.
I figured out a solution just after 1 AM, which left me 3.5 hours of sleep for my 4:30 wake-up time, for which I am grateful to Google search (but not to Apple which had no official solution to this problem anywhere that I could find, though discussion boards show that many others are suffering from the same issue).
Solution: download iTunes 12.3* and install it on your Mac**. Yes, even though the correct version is already installed. The version number will be identical to before, but it makes the iPhone Personal Hotspot feature work. The iTunes install (or some side effect of the installation) must contain some kind of support for the Personal Hotspot. I hope that it continues to work over the next 10 days while traveling.
* iTunes exemplifies everything that is bad on OS X today: a riot of confusing modal areas that anyone on the iTunes team should be personally embarrassed with. Old friend Dave H, are you still in charge of this dreck? You never had such low standards years ago.
** Maybe the latest iTunes upgrad/install was the issue and not iOS 9.0.1? Not sure, but discussion boards suggest that something in iOS is involved. I never had issues with iOS 8 however, so I think it is an iOS 9 issue.