Recently, US carrier AT&T announced the rollout of a Lumia Cyan update with new Windows Phone 8.1 for the Nokia Lumia 1520.

But those who are running Windows Phone 8.1 Preview for Developers on the Lumia 1520 did not receive the Lumia Cyan update, whereas those on Windows Phone 8 did install the update.

It then appeared the Lumia devices running Preview for Developers and using BitLocker full disk encryption were having a problem while upgrading to Windows Phone 8.1, which resulted in locking of the phone.

However, the issue is not limited to Lumia 1520 users on AT&T but to all who are on Preview for Developers.

Microsoft has acknowledged the issue and halted the Preview for the Developers programme.

We are currently investigating the issue. We have paused delivery of the update to customers using the Preview for Developers, and will resume once a fix is in place. Customers whose phones have been affected should use the Nokia Software Recovery Tool to return your Lumia to a normal commercial software state before downloading the Lumia Cyan update."

Nokia Lumia users who are facing the problem and wish to install the Lumia Cyan update on their devices should downgrade the OS to Windows Phone 8. After downgrading, users can install Windows Phone 8.1.

Those who wish to downgrade their Windows Phone 8, may follow the step-by-step guide. Before following the installation guide, users are advised to keep a backup of all data, as the process might wipe out all data. Navigate to Settings>> Backup>>App+settings>> Back up now.

IBTimes UK reminds its readers that it will not be held liable for any damage to the device.

How to downgrade Nokia Lumia from Windows Phone 8.1 Preview for Developers to Windows Phone 8

Step-1: Install necessary software to restore the Nokia Lumia device to Windows Phone 8

Download links

Nokia Recovery Software Tool (US)

Nokia Recovery Software Tool (UK)

Step-2: Proceed to install the software on Windows 7 or above

Step-3: Open the Nokia Software Recovery tool

Step-4: Connect the Nokia Lumia Phone to the computer using USB cable

Step-5: You should see which software version is compatible for the Lumia smartphone. Click install

Step-6: You will have to acknowledge that the data and content on the phone will be erased. Make a backup of phone by navigating to Settings>> backup. Also know that photos, music and apps will be wiped out in this reset process. Click that you understand then click Continue

Step-7: The Nokia software should now start installing and would take about 15 minutes to complete

Step-8: During the installation process, do not use the phone or disconnect the cable

When the Nokia Lumia smartphone restores Windows Phone 8, you can download the Lumia Cyan update featuring the latest Windows Phone 8.1. Then, perform a hard-reset so that the operating system can offer the Restore process from the backup created in the beginning of the installation process.

[Soucre: WPCentral]