Excitement turned into despair for many iPhone and iPad users after upgrading to Apple's new operating system iOS 9, as they couldn't toggle the cellular data switch, which means no access to iOS apps like Facebook, Twitter, WhatsApp and YouTube.

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Apple then released iOS 9.0.1 with several fixes, including the custom APN issue. But it offered no solution for the cellular data issue, reported iOS9News. 

Though the upcoming iOS 9.0.2 version might come with a solution, its release is expected only in next month, which means iPhone and iPad users will have to wait for a while.

There are no foolproof solutions to the problem at the moment except to try out some ways experts have suggested.

Here are possible solutions to iOS 9 and 9.0.1 cellular data issue:

  1. Try some simple things like resetting network settings, check if cellular data is enabled, reset APN settings, and factory reset.
  2. If nothing works and you can't wait for Apple to come with a solution, the only option left is to downgrade to iOS 8.4.1. However, it should be done as soon as possible because one can't do that once Apple stops signing the older version. Make sure that the company still signs the older OS before downgrading from iOS 9 or 9.0.1 to iOS 8.4.1. [READ: Step-by-step guide to downgrade from iOS 9 to iOS 8.4.1] 
  3. A Reddit user named Guy Fleegman has claimed that cellular data works on iOS 9 if mobile data is enabled for all apps on iOS 8.4.1 before updating to new OS. He suggested these simple steps:
    - downgrade to iOS 8.4.1

           - restore from backup

           - Enable mobile data for all apps

           - upgrade iOS 9.0 OTA (over-the-air)

            - you should be able to toggle mobile data now

            [NOTE: You should try this step at your own risk]

It may be noted that it is still not known when Apple will solve iOS 9 and 9.0.1 cellular data issue. The upcoming iOS 9.0.2 version is the only hope, but a solution is not guaranteed.