Basic troubleshooting for backup error alerts

Gather information around the error to determine its severity and potential causes.

• Error messages will vary depending on which backup agent software is on the protected machine or if the backups are agent-based or agentless.

• Check to see if a backup has completed successfully since the time the error occurred. If a backup has completed successfully, the error may have been transient or could be due to a conflicting task on the server.

• If a backup is currently running after you received a failure alert, it could complete successfully when it retries. When a server has VSS errors, a backup may fall back to a crash-consistent mode and then complete successfully.

If the backups continue to fail, searching the knowledge base or reviewing the error codes below can assist in determining the issue and ultimately resolving them.

Alert codes

Some of the more common codes are provided below.

Category	Code	Type	Description
Agent alerts (AGT)	AGT0900	Warning	Agent pairing failed, will re-attempt
	AGT0910	Critical	Agent pairing failed, giving up
	AGT0915	Critical	Agent pairing failed, giving up
	AGT0930	Critical	Blank hostname in certificate pair
	AGT0940	Critical	Curl Keyfile is empty, request failed
	AGT0950	Critical	Curl Keyfile is missing, request failed
	AGT1310	Warning	Metadata XML is invalid
	AGT1330	Warning	XML Parser threw an error in gettingAgentData related to version
	AGT1340	Critical	Curl returned and HTTP Error state. State was #[STATE]#
	AGT1350	Warning	Curl returned false to agentinfo
	AGT1360	Warning	Connectivity Failed. Agent Info Request Aborted
	AGT1960	Warning	$volName for $hosname has been included for backups
	AGT2016	Critical	Unable to get agent due to error 401 Unauthorized
Backup (BK/BAK)	BKP0013 / BAK0013	Critical	Cannot connect to the host - aborting snapshot
	BAK0020	Warning	The following volumes are missing:
	BKP0022 / BAK0022	Warning	Agent Driver is not loaded. Please restart the system to load the driver
	BKP0203 / BAK0203	Error	VSS Export error occurred mid-transfer - falling back to [STC|DBD]
	BKP0100		Snapshot Requested
	BAK0201	Warning	$engine Export error occurred mid-transfer (if able to reattempt)
	BKP0300		Snap was successful, returning true from takeSnap
	BKP0510 / BAK0510	Error	No Volumes have been selected for backup
	BKP0613 / BAK0613	Critical	Clearing needsBackup file
	BKP0615 / BAK0615	Critical	Backup skipped due to not enough free space.
	BKP1201	Critical	Export error occurred mid-transfer: {$error}
	BKP1410	Critical	VSS Promised more data than was received. This likely means some volumes failed to be backed up.
	BKP1430	Warning	The backup job stalled longer than $timeOutLimit seconds and was cancelled
	BKP1450	Warning	RollBack - The backup job was unable to complete. One or more volumes may have failed to be backed up
	BKP1615 / BAK1615	Warning	Disk is nearly full (only <space> GB left), backup may fail...
	BKP1630	Warning	Unable to retrieve agent metadata
	BKP1640	Warning	Unable to read cached agent info
	BKP1650	Warning	Backup failed as Backup job was unable to be assigned
	BKP1660	Critical	VSS Snap took more than $timeout seconds; canceling backup.
	BKP1665	Error	Backup canceled due to VSS snapshot timeout ($timeout seconds)
	BKP1670	Critical	cURL reports connection problems to the agent. Failed to start backup.
	BKP1675		Backup did not start because there was a problem communicating with the Replay agent.
	BKP1680	Critical	Authentication error while communicating with SnapToVM; unable to start backup
	BKP1685	Error	TakeSnap returned HTTP Error State 401. The Siris was unable to correctly authenticate to the agent.
	BKP1690	Critical	Unknown headers received - {$result['header']}
	BKP1695	Error	Received an unknown HTTP response code ({$result['header']}) from Replay
	BKP1700	Critical	HTTP {$headers['http']} error received. Assuming that backup failed and giving up. Writing XML response to {$keyBase}{$hostname}.snapFailXML
	BKP1705	Error	TakeSnap returned HTTP Error State {$headers['http']}.
	BKP1710	Warning	XML Parser threw an error in UpdateStatus
	BKP1715	Warning	The backup job was unable to complete.
	BKP1720	Warning	Export error occurred during backup: {$error}
	BKP1725	Warning	Snapshot transfer stalled out.
	BKP2013	Warning	Unable to connect to the host.
	BKP0211	Warning	VSS Failure Occurred Mid-Transfer.
	BKP2126	Warning	NAF snapshot failure
	BAK2040	Warning	Unable to create disk images for backup of .$hostVol['mountpoints']
	BKP2040	Warning	Error creating or repairing partition for image file: <file> Exception: <exception>
	BKP2202	Warning	Backup failed as job ( $thisJob ) was unable to be assigned
	BKP2502	Warning	Bad HTTP error code - . $header['http']
	BKP2615	Warning	Unable to retrieve agent metadata
	BKP2618	Warning	The machine wants to perform a full backup, but there is not enough space on the device for that.
	BAK3000	Critical	Critical backup failure: Backup attempt _ of _
	BKP3031	Critical	Backup is hung and cannot be stopped
	BKP3201 / BAK3201	Critical	$engine Export error occurred mid-transfer
	BKP3300 / BAK3300		Snap was successful, returning true from takeSnap
	BKP9880	Warning	More than four drives present, please select SATA or SCSI from Advanced Options
	BKP4000	Warning	Backup wasn't taken in over 24 hours.
	BKP4010	Warning	Backup wasn't taken in over 24 hours. - Backup stuck in queue
Network Attached Storage (SNS)	SNS005	Error	Cannot snapshot - $e->getMessage()
	SNS006	Error	Snapshot for NAS Share {$hostname} FAILED.
	SNS1010	Error	Snap already in progress for volume
	SNS003	Error	Share $name does not exist
	SNS020	Critical	Cannot load share - $e->getMessage()
	SNS017	Critical	called when MLocateDBBuilder->build() throws an exception
Snapshot (SNP)	SNP0100 / BAK0100		Snapshot Requested
	SNP0126		NAF snapshot failure
Screenshot (SCN / SCR)	SCN0831		VM Screenshot Successful
	SCN0862		Command Complete HTTP code
	SCN2863		VM screenshot TIMED OUT and FAILED to boot correctly. VM RAM is less than 512MB. OCR Text:
ZFS filesystem (ZFS)	ZFS3985	Warning	File-System could not properly remount. Please contact Support immediately and submit a ticket.
	ZFS3987	Warning	The ZFS File-System for $hostname is not mounted. Cannot proceed with backup. Please contact Support immediately and submit a ticket.
	ZFS4150	Critical	ZFS snapshot failed.
	ZFS4160	Warning	ZFS is busy waiting $zfsTimeout seconds and trying again.

Additional categories include:

• DEV Device
• ENC Encryption
• FLS Filesystem related
• HIR Hardware Independent Restore
• ISC iSCSI
• LIC License
• LOP Loop Device
• PKG Packages
• PRO Proactive issue detection
• RET Retention
• SYN Speedsync
• MAL Malware
• VRT Virtualization

Ensure you've met prerequisites

Getting Started articles are available that include minimum system and networking requirements for each of the backup types. Check and verify that your system meets these requirements.

• Getting started with the Datto Windows Agent
• Getting started with the Datto Linux Agent
• Getting started with agentless backups

System Health

Confirm the system is healthy by reviewing each of the following on the production machine. If a protected machine is not running properly, it can cause issues creating a healthy and consistent backup.

VSS

Microsoft VSS is an essential component in successful Windows backups. Many factors affect VSS functionality, including:

• Disk health
• NTFS filesystem health
• Free space
• Disk fragmentation
• Disk I/O
• Disk permissions
• Antivirus software
• Windows updates

To check the status of VSS writers before starting a new backup:

1. Open a Windows CMD prompt as an administrator on the protected machine.

2. Run:

   vssadmin list writers

3. Review for any writers in a failed or hung state.

The above command will list out all the writers on the protected system. A healthy writer will have a state of "stable." A VSS writer can only be used by one application at a time, so if you see a writer listed as waiting for completion, that indicates another application is currently using that writer.

See the following Knowledge Base articles for more information on resolving VSS issues:

• VSS: Description, Compatibilities, and Troubleshooting Resources
• Resolving VSS Writer Errors in Windows 8, Server 2012, and Up
• Error: "VSS quiescence failed"

Task Scheduler

• Check scheduled tasks on the protected machine for anything that may have been running during the time the error occurred. Scheduled ShadowCopy Jobs can cause VSS conflicts during Datto device backup times.
• Check for defragmentation applications. Sometimes these applications will disable VSS during the defragmentation process.
• Check for other backup software that might still be running. Datto does not recommend running more than one backup solution on your protected machine; doing so will cause conflicts in most cases.
• If the server is running Microsoft SQL, SQL backups can also cause VSS collisions. Take note of when these are running in SQL Studio. Reschedule backups, so they don't run at the same time and conflict. See Best-practices for backing up and restoring Microsoft SQL databases for more information.

Services

• Open the Services console on the protected machine to verify that the required services are running.
• The required services for Datto Windows Agent can be found in Datto Windows Agent: Unable To Start Backup Because Agent Service Is Stopped

Server resources

• You should have at least 1 GB free memory available during normal operation for the backup process to function without issues.
• CPU utilization will increase when the system is taking a VSS snapshot.

Disk fragmentation

• VSS application freeze cannot exceed 60 seconds, or the operation will time out. Highly fragmented systems may produce errors in regards to "flush and hold" taking too long.

Free disk space

• You need at least 20% free space on the protected machine for snapshot copy-on-write operations.
• Windows requires a 15% free disk space for defragmentation to work properly.

Event logs

• Review Windows Application Logs in Windows Event Viewer.
• Filter for event sources for VSS around the time of the backup error.
• If you find event VSS errors in the event logs, research the event id with Microsoft. The resolution of VSS errors will help backups run successfully.

• Once you have researched your error and taken steps to resolve the backup failure, manually start a backup for the agent from the Protect tab of the Datto Remote Web.

• If you get a different error, research and troubleshoot that error as well. If you are stuck and the backup continues to fail, you can contact Datto Technical Support.

The ticket should contain the following information:

• The error that has occurred.
• Time of the error.
• Protected system name.
• Any articles you have referenced.
• Any troubleshooting steps that you have taken.

This information will help to avoid repeating steps and allow Datto Technical Support to resolve the issue as soon as possible.