Announcing Windows 10 Insider Preview Build 17101 for Fast & Build 17604 for Skip Ahead


Hello Windows Insiders!

Today, we are releasing Windows 10 Insider Preview Build 17101 (RS4) to Windows Insiders in the Fast ring. We are also releasing Windows 10 Insider Preview Build 17604 (RS5) to Windows Insiders who have opted into Skip Ahead.

Flighting to Skip Ahead

Right now our focus is on stabilization for RS4. As part of the stabilization process, we have “forked” RS4 into its own branch called “RS4_RELEASE” just like we did with RS2 and RS3. Going forward – RS4 builds will come from the RS4_RELEASE branch. This also means that we intend to release new RS4 builds to Insiders more quickly to both the Fast and Slow rings as these builds we include mostly bug fixes.


In RS3, we experimented with the idea of flighting two different releases at the same time with something we called Skip Ahead. A subset of Insiders were able to choose to “skip ahead” to the next release of Windows 10 and receive builds from RS4 while we were finishing up RS3. That experiment went well as our engineering teams benefited from the early feedback. So we’re going to do it again!


For complete details on this build, please consult the Windows Insider Blog.

1 Reply



I just started testing the RS4 preview build today. Noticed that sysprep seems to be broken. Immediately after a sysprep /generalize /shutdown, seeing a message box with 'a fatal error occurred while trying to sysprep the machine'.  Panther error logs 'machine is in an invalid state or we couldn't update the recorded state'.  Made sure not to have any network connectivity no additional MS Store Apps got installed and even removed all appxpackages and appxprovisionedpackage via powershell (which was an issue before with sysprep in RS3).  Any ideas ?