When Windows 10 Technical Preview launched, a lot of you complain that they can not download the new OS (Windows app Insider message “No Build“) while using a device in the list of Microsoft support. Especially this situation is pretty much for the Lumia 730 and Lumia 630. I had a walk through the forums and found a Microsoft employee replies Windows Insider program on this issue, accompanied by solutions. Try it yourself. I saw many of you also do the same manner and got Windows 10.

You may want to read these posts first:
How to install Windows 10 Technical Preview for Phone (Lumia 630, 635, 730 and 830 only)
The new features in Windows 10 Technical Preview for phone

This Hack Lets You Install Windows 10 on Any Windows Phone

When you enroll as a Windows Insider, you will be prompted to choose how quickly you receive updates by selecting either “Insider Slow” or “Insider Fast”. 

Windows10 Enroll Fast
Windows10 Enroll Fast

If you selected “Insider Slow”, you will not be offered the latest build immediately after it is released.  Once some time has elapsed to allow us to find some solutions for common issues with a particular build, it will be offered to users who selected “Insider Slow”.  To get the latest build immediately:
  1. Open the Windows Insider app on your phone and select Get preview builds.
  2. On the Enroll page, select the Fast setting.
If you selected “Insider Fast”, and you still aren’t offered the upgrade, on some devices there is a software conflict that will prevent a successful update to Windows 10 Technical Preview for phones.  When this conflict is detected, no software updates will be shown for installation.
To find out if your device has this conflict, please check the OS version installed.
  1. Navigate to Settings > About > (more info)
  2. View the OS version.  If your device shows 8.10.14226.359 or greater, your device has this conflict.  Devices with other OS versions do not.
Should your device have the conflict, please follow these steps to update to Technical Preview:
  1. Double-check to make sure your phone is on the list of supported devices for Technical Preview.  If your device is not supported, you cannot install Technical Preview at this time.
  2. Using the Windows Phone Recovery Tool, begin the process to re-flash your device.
    • Windows 10 for phone Recovery Tool
      Windows 10 for phone Recovery Tool

      This will recover the device to a software build that does not have the conflict.

  3. After the re-flash is complete, DO NOT CONNECT TO WI-FI.  This step is critical to prevent the device from automatically taking a background update to the OS version that contains the conflict.
  4. Once you reach the Start screen, go to Settings > Phone update and uncheck the box for “Automatically download updates if my data settings allow it”.
  5. Perform a power cycle on the device, turning the device off and then back on.
  6. Turn Wi-Fi on and download the Windows Insider application to the device
  7. Launch the Windows Insider application and select the desired Insider state (Slow or Fast).
  8. Go to Settings > Phone update and tap Check for updates.
  9. Accept the update and follow the on-screen directions to complete the process for updating to the Technical Preview.

See also:
How to install Windows 10 Technical Preview for Phone (Lumia 630, 635, 730 and 830 only)
The new features in Windows 10 Technical Preview for phone

This Hack Lets You Install Windows 10 on Any Windows Phone