The company noted that an increasing number of iOS devices froze when reaching the "Slide to Upgrade" phase of the update to iOS 9. After complaints piled up from iPhone and iPad users who got stuck in the update process, the company revealed a workaround the issue.

Apple's technical support staff recommends a radical solution to the problem: a factory reset of the blocked iPhone, iPad or iPod and simply reloading it from an existing backup point. This workaround is the only one that should make all devices functional, as other methods seem to only offer partial results. The method has an obvious downside for anyone who did not do a backup, as they will remain without any data on their phones, tablets or MP3 players.

The angry reactions are understandable, especially from users who are using their devices as work tools: contacts, calendars, message archives and personal notes are all gone in a second due to a software fluke.

"I have just updated my iPad to iOS 9 and found to my horror that once it has 'successfully' installed and then gone through the initial setup phase, I cannot progress past the second request to 'slide to upgrade' page," a dismayed user of The Register complains.

After following the correct setup order - enter the password, slide in order to upgrade, select the Wi-Fi, slide to upgrade again - some Apple users discovered that their device is still nonresponsive. A part of them reported that they completed the reboot strategy and reverted to the initial factory settings just to discover that it still didn't fix the issue.

Repeating the whole Apple proposed solution a couple of times seemed to do the trick, but the multiple attempts necessary costs the users time and patience.

Before users decide to revert to factory setting and lose all the data, they should follow the guide Apple provided for those poor souls who are stuck in the 'Slide to Upgrade' screen limbo. Users just have to connect the iOS device with iTunes and try a force restart of their devices.

Numbers show that a majority of users stricken by the technical mess were attempting to skip directly from iOS 7 to iOS 9. The iPhone producer refused to confirm if that was causation or mere correlation. Earlier this week, the WatchOS 2 update had to be reprogrammed after a number of bugs were discovered in the Apple Watch firmware.

Apple promised it will fix the bug in a future iOS update. Until then, it is highly advisable to make backups before any Apple upgrades.