On December 2nd, Microsoft released an update (KB3020114) for Windows 10 Technical Preview build 9879. This update was intended to fix frequent Explorer.exe crashes. Unfortunately for 12% of Windows 10 testers, this update failed to install. Microsoft has acknowledged the issue and has offered an explanation as well as a workaround.
Microsoft released this update so Windows 10 users had particular glaring issues addressed since no new build is scheduled to be released until January. Unfortunately, this particular update was causing Explorer.exe to crash due to the following reasons:
- A new System Compression code that systems with SSDs can take advantage of to reduce disk usage by the OS. In some cases the logic for low-space detection gets inverted, and we compress automatically as a background operation.
- On PCs have had system compression enabled, an additional bug with how the filesystem tracks deletes caused the installer to think that the temp files failed to extract correctly, so the installer fails because it thinks it cannot complete.
Microsoft has issued a workaround for those of you who have the install issue:
- Restart your PC
- Open CMD.exe as an Administrator and run: compact /u /exe /s:%windir%\winsxs\filemaps
- Immediately afterwards run Windows Update and Check for Updates
- Install KB3020114
- Restart when prompted
Microsoft has also stated that this update was not pulled since the ‘audience is technical.’ As Microsoft puts it, bumps like these are unfortunate but are a part of the engineering process.
Further reading: Microsoft, Security, Windows 10
On a shipping OS, if we hit an issue like this we’d normally pull the update. But since the Windows Insider audience is technical we decided to leave it up while we work on the fix so that people hitting the Explorer crash can get some relief. We need to fix the 2 underlying issues above, and make sure that no additional problems prevent hotfix installs in the process. We’ve been working on this since last week but it will take a bit more time to ensure we got it right.
We appreciate your patience on this, and again THANK YOU for being a Windows Insider. While bumps like this are unfortunate they are a part of engineering a new OS. You’re seeing everything early (flaws and all) as we build this together. The good news is that your help is allowing us to find and fix these issues much faster than in the past, which means that the final product will be higher quality as well as having features shaped by your feedback.