The latest version of Apple's operating system was officially made available to the public only a couple of days ago but users who have upgraded to the new platform are already reporting about its annoying issues.

The newest problem uncovered by users is a bug that prevents them from using apps if they're not connected to a Wi-Fi network.

According to a report from Beta News, the iOS 9, like other versions of the platform, lets users pick apps which will run on cellular connection. This is a practically way to conserve data and minimize expenses.

Users will be able to this by heading over to the Settings menu and clicking on the "on" button to activate cellular data for certain apps. However, due to a bug that affects the firmware, this customization will revert back to its default setting after leaving the Settings menu.

Because of this, users will not be able to use certain apps such as Facebook and Google Maps unless they tap into a wireless network.

According to Wayne Williams, the author of the report published by Beta News, he experienced the problem after upgrading his iPhone 5S from the iOS 8 to the newest version. He also purchased an iPhone 6S which unfortunately, also has the same bug that affects his app usage activity.

Based on the comments of users on Apple Support Communities, it seems Williams is not the only one experiencing the same issue.

"I disabled most of the apps from the mobile data setting page before I left, so I could read mailabroad without using a lot of data in the background," user ElOllos wrote. "After upgrading to iOS 9, I can't seem to enable mobile data for my new apps."

"The ones that were already enabled are fine," the user added. "They can be disabled and then enabled again, but, for example, Spotify refuses to use mobile data after the update."

After consulting Apple and reading other users' comments, Williams noted that he has two options that can possible resolve the issue. He can either go back to a previous version of iOS or set-up his iPhone as a new device, which involves removing all of the apps and installing them again one by one, PC Mag reported.

As expected, the first version of the iOS 9 contains bugs. This is almost the same situation that Apple found itself in during the first release of the iOS 8. Based on previous experiences of users, it is always advisable to wait for an updated version to be released, or one that contains all the necessary bug fixes and patches, before upgrading to a new platform.