Windows 10 Mobile build 14977 failing with error 8007007B for some users

After weeks of waiting, Microsoft is now releasing a new test preview for mobile devices. This time the company is pushing Windows 10 Mobile build 14977 to the Fast ring with a small set of improvements and changes, and Microsoft Edge on mobile get support for epub file format.

However, some phones may get the error 8007007B, which causes the phone to fail to install today's update. There is a Microsoft community forum thread dedicated to the topic, which was known prior to the update going live.

Indeed, the same error was noted in the original changelog notes posted for the build's announcement. Microsoft said this error may be seen on devices with "8GB of internal storage such as the Lumia 550".

Microsoft explains that if you come across error 8007007B you won't be able to install this flight. Furthermore, the company notes that there isn't a workaround, and you'll have to wait until the next Windows 10 Mobile build.

It's also worth pointing out that this issue isn't affecting all devices "and there is no long-term harm from encountering it." In the case, your handset hits error 8007007B; the installation will simply fail, and the device will revert and boot to the previous version of the operating system.

Microsoft is also ensuring that it's aware of the problem and it's working on a solution for those affected devices.

Did you come across error 8007007B while installing build 14977 on your mobile device? Tell us in the comments below.

Mauro Huculak

Mauro Huculak is technical writer for His primary focus is to write comprehensive how-tos to help users get the most out of Windows 10 and its many related technologies. He has an IT background with professional certifications from Microsoft, Cisco, and CompTIA, and he's a recognized member of the Microsoft MVP community.