WinRE troubleshooting features
If a Windows device can't start, it automatically fails over to the Windows Recovery Environment (WinRE). The Automatic Repair tool in WinRE automatically diagnoses and repairs a Windows installation that can't start. WinRE is also a starting point for several tools that you can use to manually recover a system. This topic describes the automatic failover behavior, manual diagnosis, and repair process in WinRE.
Recovering from startup failures
When Windows starts, the Windows loader sets a status flag to indicate that the startup process has started. Windows typically clears this flag before the Windows sign-in screen appears. However, if the startup operation fails, Windows doesn't clear the flag. The next time that the computer starts, the loader detects the flag, assumes that a startup failure occurred, and starts WinRE instead of Windows.
The behavior that detects startup failures relies on the completion of the startup process rather than a Windows error. For example, a false positive may occur if power is lost during startup. In such a case, your user starts WinRE even though the Windows installation started up.
Because the behavior that detects startup failures (also referred to as boot failures) relies on the Windows boot manager and the Windows boot loader, some failures can make WinRE inaccessible. In the following scenarios, your user has to use the bootable WinRE media to start and recover the computer:
- Corrupt disk metadata exists in the master boot record (MBR), partition table, or boot sector of a WinRE partition.
- The boot manager is missing or corrupted.
- The Boot Configuration Data (BCD) store is missing or corrupted.
If the boot loader can't read or write to the boot status flag, Windows doesn't automatically fail over into WinRE. However, your user can still use the Boot Options menu to manually start the on-disk WinRE environment.
Advanced troubleshooting utilities in WinRE
Your user can manually start several system recovery tools after starting the on-disk WinRE environment by using the recovery media, or from the Boot Options menu. With the exception of Automatic Repair, the Windows Assessment and Deployment Kit (Windows ADK) doesn't include these tools. Push-button reset is the recommended recovery solution in Windows.
The Automatic Repair tool automates common diagnostic and repair tasks for non-bootable operating system installations. Automatic Repair starts if the computer fails over into WinRE because of a detected startup failure. If the computer can't fail over to an on-disk instance of WinRE, your users can also use a WinRE CD or DVD to start Automatic Repair as a manual recovery tool.
System Image Recovery
Use System Image Recovery for file backup and system image backup. System Image Recovery requires an external storage device. For file backup, your users can let Windows choose what to back up, or they can select individual folders, libraries, and drives. By default, backups are created on a regular schedule. Your users can change the schedule and manually create a backup at any time. After your user sets up System Image Recovery, Windows keeps track of the new or modified files and folders, adding them to the backup.
For system image backup, your users can create a system image or an exact image of a drive. A system image includes Windows and system settings, programs, and files. Your users can use a system image to restore the contents of their computer if the hard disk drive or computer stops working.
If your users restore their computer from a system image, the restoration is a complete restoration. Your users can't choose individual items to restore. All of the current programs, system settings, and files are replaced.
If you set up a scheduled file backup, you can include a system image with only the drives Windows requires to run. You can manually create a system image if you want to include additional data drives.
Previous system image versions are copies of the files and folders that Windows automatically saves as part of the system protection process. Depending on the type of file or folder, your users can open a previous version, save the version to a different location, or restore a previous version. Your users can use these previous versions to restore accidentally modified, deleted, or damaged files or folders. However, because Windows replaces these files with new versions, the files won't be available if the drive fails.
Using tools from a Command Prompt window
All Windows PE command-line tools are available from a Command Prompt window (cmd.exe). For example, you can use Registry Editor (Regedit.exe), which includes command-line switches, to modify the Windows registry. Or, you can use the Chkdisk.exe tool to troubleshoot and fix volumes. For more information, see Registry Editor, Chkdsk, and Troubleshooting Tools and Strategies.
"Not enough memory resources" error when you open a Command Prompt window in Windows PE for Windows 10, Version 1803
You open a Command Prompt window in one of the following scenarios:
- You use a Windows 10, version 1803 Windows PE image.
- You start Windows 10, version 1803 in WinRE.
- You start the computer by using Windows 10, version 1803 installation media.
In this scenario, you receive a message that resembles the following:
Not enough memory resources are available to process this command.
You expected to receive a message that resembles the following:
(c) 2018 Microsoft Corporation. All rights reserved.
What you should know:
- There is no low-memory condition.
- This issue does not affect any functionality.
- You can safely ignore this error.
- This error has been corrected in the next version of Windows 10.
This issue occurs because a resource file is missing from the components that are responsible for storing these copyright strings. As a result, when Windows opens the Command Prompt window and tries to read the string, it can't find it. Windows assumes that it couldn't read the string because of a low-memory condition.
Custom support and recovery tools
Computer manufacturers can provide custom support and recovery tools. These tools will vary by manufacturer. For more information, see the manufacturer-provided documentation.