Failed screenshot with blank image or image of Windows loading
Topic
This article describes the possible causes and solutions for screenshot failures with a completely or partially blank screen.
Environment
- Datto SIRIS
- Datto ALTO
Description
This issue is caused by the timing of the screenshot compared to the amount of time it takes to boot the protected machine on the Datto device. If the virtualzation is still loading the operating system when the screenshot takes place, then it may display a blank screen. Additionally, the operating system loaded and was idle for too long before the screenshot was taken, causing it to go idle or load a screensaver. 
Identifying the cause
Manual local virtualizaion testing of the protected machines backup can confirm:
- bootability of the backup point
- the amount of time required to fully load the operating system
- the amount of time it will idle at the login screen before going to sleep/power saving
SIRIS devices
Mount a local virtualization of the affected server from the Datto appliance's GUI. Set the virtualization's resource allocation to 1 CPU core and 2 GB of RAM. Start the virtualization, and observe the amount of time the VM takes to boot to the Windows login screen.
If the production machine has a screensaver configured, observe the amount of time it takes for the screensaver to turn on in the VM.
Stop and unmount the virtualization. Navigate to the Protect > Configure Agent Settings tab of the Datto Device GUI. Adjust the amount of time the virtual machine needs to wait before taking a screenshot using the Screenshot Verification drop-down.
Adjust the screensaver wait time on the production machine to allow enough time for the virtualization to boot, and for the Datto appliance to capture a screenshot. The default Windows power setting turns off the screen after 10 minutes of inactivity. Long Additional wait times may exceed this threshold. Setting this threshold to "never" will resolve the issue.
Start a backup for the production machine. Wait for the backup to complete.
Force a new screenshot verification, and observe the results.
ALTO devices
ALTO devices use hybrid virtualization to launch VMs in the cloud, rather than on the local device. However, the screenshot is produced on the local device. This makes timing the virtualization launch, as outlined above, an unreliable method of estimating additional wait time for ALTO devices. We recommend testing screenshots with varying additional wait times to determine the additional time required.
Adjusting the timeout
Once the backup point is confirmed to be bootable and the expected boot time is established, the additional wait time may be set for the agent. This will allow a delay before the screenshot is taken, to give the protected machine enough time to load to the login screen.
For information on configuring the timeout, refer to Screenshot verification settings.
Additional Troubleshooting
If additional issues are causing a delay in the boot of the protected system on the datto device, it can lead to an inconsistent boot time.
Video controller
If adjusting the verification and screensaver times does not resolve the issue, you can change the Virtualization Video Controller to the Cirrus setting. This setting is found on the Remote Web, at Protect > Configure Agent Settings > Advanced.
Windows Updates
If the production machine has pending Windows updates, this state will be replicated to all snapshots taken of it from the time the updates became available until the time that they are installed. This can cause screenshots of the protected system to appear blank, because the pending Windows updates are attempting to install in the virtual environment, causing the boot process of the screenshot VM to take longer than usual to complete.
To correct this issue, you can install the pending Windows updates on the production machine and take a new backup. Alternatively, you can increase the Additional Wait Time setting for the protected system to allow the agent more time to boot fully before your Datto appliance attempts screenshot verification.
Dell Data Protection
Dell Data Protection(external link) may cause failed screenshots showing a blank screen and a cursor. If this service is enabled on the production machine, attempt another backup after disabling it.
