Bricked and Windows 8.1 Lumia 520/521 devices and problems receive fix from Microsoft

By Staff Writer

Apr 22 2015, 09:59 AM EDT

Lumia 520/521 users previously reported bricked devices when trying to revert to Windows 8.1 after updating to Windows 10 Technical Preview. This led Microsoft to pause the roll out of the build to these devices. However, this is now fixed as Microsoft resumed the release of the Windows 10 Technical Preview builds.

The cause of the problem was due to some devices having "trouble accepting the recovery image data being flashed. The blocks of data were too large for some devices to handle, and the memory on the device was having trouble with the speed at which the data was being written. In short, devices were getting too much data, too quickly. This would cause the failure as the new software is corrupted."

To fix the issue, Microsoft made two key changes, "We will be lowering the size of the data blocks being fed to the device during recovery (lowering from 2MB down to 128kB), and we will also be slowing down the data writing speed (from 8MB/sec to 5 MB/sec)."

The testing is said to have showed "promising results from these changes." Microsofit also said that the company will turn the update path back on for these devices "once we're confident in the results."

Now, this was confirmed through the response of Microsoft Insider Program head Gabriel Aul to a query by a Lumia 525 user. A user was asking in Twitter about the rollout status of the Windows 10 Technical Preview build. Here's what Gabriel Aul said:

@mrartnov We paused offering builds for 52x while we worked through an issue reported on those phones. That is resolved, will reoffer soon.
— Gabriel Aul (@GabeAul) April 20, 2015

Based on Aul's statement, users can expect that the Windows 10 Technical Preview (build number 10051) for Lumia devices is now rid of issues once it gets rolled out. He also gave a hint that non-Lumia Windows Phone users will have the opportunity to download the Windows 10 for Phones. But, he did not give additional details especially the roll out date of the Technical Preview.