Troubleshoot Windows Compute Engine instance boot issues

Windows

This document helps you find out why your Windows Server Compute Engine instance fails to boot and fix common issues.

A Windows compute instance that fails to boot usually shows these symptoms:

The compute instance is in the RUNNING state, but you can't connect to it by using RDP.
Serial port 1 shows only firmware and guest agent lines, and the guest agent never reports that it is ready.
Serial port 2 shows a Windows Boot Manager error screen or a STOP error.

If the compute instance finishes booting but you can't connect to it, then see Troubleshooting RDP.

Before you begin

Make sure that the compute instance writes output to serial ports 1 and 2. Serial port output is available while the compute instance runs; to keep it after the compute instance stops, enable serial port logging to Cloud Logging. For more information, see Viewing serial port output.
If you haven't already, set up authentication. Authentication verifies your identity for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:
1. Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:
```
gcloud init
```
  If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
  
  Note: If you installed the gcloud CLI previously, make sure you have the latest version by running gcloud components update.
2. Set a default region and zone.

Automatically detect the cause

Run the boot diagnostic command. For a Windows compute instance, it reads serial port 2, reports the most likely cause, and links to the matching section in this document:

To use this command, make sure that you have installed the alpha commands component.

gcloud alpha compute diagnose boot INSTANCE_NAME --zone=ZONE

Replace the following:

INSTANCE_NAME: the name of the compute instance.
ZONE: the zone that contains the compute instance.

Read the serial console output

To read the Boot Manager screen or the STOP error yourself, read serial port 2:

Console

In the Google Cloud console, go to the VM instances page.

Go to the VM instances page
Select the compute instance for which you want to view serial port output.
Under Logs, click Serial port 2 (console).

gcloud

gcloud compute instances get-serial-port-output INSTANCE_NAME --zone=ZONE --port=2

Replace the following:

INSTANCE_NAME: the name of the compute instance.
ZONE: the zone that contains the compute instance.

The Boot Manager screen contains a Status: line with a code such as 0xc000000e, and an Info: line that describes the failure. A STOP error contains the STOP code and its name, for example INACCESSIBLE_BOOT_DEVICE.

To open the Windows Boot Manager menu or the Advanced Boot Options menu on the next boot, see Troubleshooting Windows VMs.

Common boot issues

The following sections list common boot failures on Windows compute instances, their serial port 2 signatures, and how to resolve them. Most resolutions require you to attach the boot disk to a recovery VM, as described in Fix the disk offline.

Windows Boot Manager can't start Windows

Symptom: Serial port 2 shows the Windows Boot Manager error screen:

Windows failed to start. A recent hardware or software change might be the cause.
Status: 0xc000000e
Info: A required device isn't connected or can't be accessed.

The status code identifies the specific cause:

Status	Meaning
`0xc000000e`, `0xc0000001`	The Boot Configuration Data (BCD) points at a boot device that the firmware can't reach. Common after a disk restore, a disk clone, or a change to the disk configuration.
`0xc0000225`, `0xc000000f`	The boot loader or its BCD entry is missing or invalid.
`0xc000014c`, `0xc0000034`, `0xc0000098`, `0xc0000102`	The BCD store is missing, incomplete, or corrupt.

Cause: The Boot Manager loaded, but the BCD doesn't describe a bootable Windows installation.

Resolution: Attach the disk to a recovery VM and repair the boot configuration by using the Windows startup repair tools, following Microsoft's Advanced troubleshooting for Windows startup issues documentation for the status code shown. See Fix the disk offline. If the boot configuration can't be rebuilt, then restore the disk from a snapshot.

BOOTMGR is missing

Symptom: Serial port 2 shows BOOTMGR is missing. Press Ctrl+Alt+Del to restart. This message appears only on OS images that use BIOS boot.

Cause: The boot manager file is missing from the system partition.

Resolution: Attach the disk to a recovery VM and restore the boot files by using the Windows startup repair tools, following Microsoft's Advanced troubleshooting for Windows startup issues documentation. See Fix the disk offline.

STOP 0x7B INACCESSIBLE_BOOT_DEVICE

Symptom: Serial port 2 shows a STOP error that names INACCESSIBLE_BOOT_DEVICE.

Cause: Windows found the boot volume, but it can't access the volume because the storage driver for the disk controller is missing or disabled. This error is common after a change of disk interface, such as from SCSI to NVMe, a storage driver update, or a restore from a different compute instance.

Resolution: Reset the compute instance once; a transient failure often clears. If the error recurs, then attach the disk to a recovery VM and enable or reinstall the storage driver for the compute instance's disk interface in the offline installation. For steps to find and remove or update the driver in the offline installation, see Advanced troubleshooting for stop code or blue screen errors.

STOP 0xED UNMOUNTABLE_BOOT_VOLUME

Symptom: Serial port 2 shows a STOP error that names UNMOUNTABLE_BOOT_VOLUME.

Cause: The NTFS metadata on the boot volume is damaged, or the disk can't be read.

Resolution: Attach the disk to a recovery VM and check and repair the volume as described in Completing an offline repair. If the volume can't be repaired, then restore the disk from a snapshot.

Other STOP errors

Symptom: Serial port 2 shows a STOP error, for example CRITICAL_PROCESS_DIED, SYSTEM_THREAD_EXCEPTION_NOT_HANDLED, or a STOP code such as *** STOP: 0x0000007E.

Cause: A required system process ended, a driver raised an exception that the kernel couldn't handle, or another kernel error occurred. The STOP line often names the .sys driver file that is responsible.

Resolution: Reset the compute instance once. If the error recurs, then read the full stack trace as described in Troubleshooting blue screen errors, and then repair the system files or remove the driver or update named in the STOP line from a recovery VM, as described in Completing an offline repair.

Fix the disk offline

Most Windows boot issues are repaired by attaching the boot disk to a recovery VM as a data disk and by running the Windows repair tools against it. For the procedure, see Completing an offline repair.

The resolutions in this document assume that the original boot disk is attached to a recovery VM. Before you change the disk, create a snapshot so that you can restore it if the repair fails. For the procedure, see Create archive and standard disk snapshots.

Restore the compute instance if the disk can't be repaired

If none of the resolutions work, then restore the boot disk from a snapshot, or create a new compute instance from a snapshot or a custom OS image and move your data to it.