The issue exists with iOS8 across platforms.
Note the message above:
"the exact message is 'To enable Personal Hotspot on this account, contact Carrier'
this issue has started online since i upgraded to ios8. i have been using this on all older iOS versions. i never had any issue. i am sure it has nothing to do with the carrier. probably some bug in iOS8 I think."
Just like the person above, I had the same experience, but with my iPhone. I had personal hotspot service on my iPhone before ioS8, regardless of whether I subscribed to it or not with my non-contract carrier. After the iOS8 upgrade, I am forced by the phone to go to my carrier---conveniently through a new menu button that pops up when you try to turn on the personal hotspot (which is unsubtly titled 'upsell' when you hover over it). Only new firmware on the device would do this.
True, it may be that Apple discovered what it, in consultation with its carriers, considered to be a bug in earlier versions of its iOS. If the case, it would be great, however, if they would be upfront about this. It erodes trust.