Merge pull request #114047 from dcurwin/a-may6-2020

VM troubleshooting

Author: PRMerger13

articles/backup/backup-azure-troubleshoot-vm-backup-fails-snapshot-timeout.md

@@ -40,6 +40,8 @@ After you register and schedule a VM for the Azure Backup service, Backup starts
 
 **Cause 4: [VM-Agent configuration options are not set (for Linux VMs)](#vm-agent-configuration-options-are-not-set-for-linux-vms)**
 
+**Cause 5: [Application control solution is blocking IaaSBcdrExtension.exe](#application-control-solution-is-blocking-iaasbcdrextensionexe)**
+
 ## UserErrorVmProvisioningStateFailed - The VM is in failed provisioning state
 
 **Error code**: UserErrorVmProvisioningStateFailed<br>
@@ -198,6 +200,14 @@ If you require verbose logging for waagent, follow these steps:
 A configuration file (/etc/waagent.conf) controls the actions of waagent. Configuration File Options **Extensions.Enable** should be set to **y** and **Provisioning.Agent** should be set to **auto** for Backup to work.
 For full list of VM-Agent Configuration File Options, see <https://github.com/Azure/WALinuxAgent#configuration-file-options>
 
+### Application control solution is blocking IaaSBcdrExtension.exe
+
+If you are running [AppLocker](https://docs.microsoft.com/windows/security/threat-protection/windows-defender-application-control/applocker/what-is-applocker) (or another application control solution), and the rules are publisher or path based, they may block the **IaaSBcdrExtension.exe** executable from running.
+
+#### Solution
+
+Exclude the `/var/lib` path or the **IaaSBcdrExtension.exe** executable from AppLocker (or other application control software.)
+
 ### <a name="the-snapshot-status-cannot-be-retrieved-or-a-snapshot-cannot-be-taken"></a>The snapshot status can't be retrieved, or a snapshot can't be taken
 
 The VM backup relies on issuing a snapshot command to the underlying storage account. Backup can fail either because it has no access to the storage account, or because the execution of the snapshot task is delayed.

articles/backup/backup-azure-vms-troubleshoot.md

@@ -93,6 +93,14 @@ Restart VSS writers that are in a bad state. From an elevated command prompt, ru
 * ```net stop serviceName```
 * ```net start serviceName```
 
+Another procedure that can help is to run the following command from an elevated command-prompt (as an administrator).
+
+```CMD
+REG ADD "HKLM\SOFTWARE\Microsoft\BcdrAgentPersistentKeys" /v SnapshotWithoutThreads /t REG_SZ /d True /f
+```
+
+Adding this registry key will cause the threads to be not created for blob-snapshots, and prevent the time-out.
+
 ## ExtensionConfigParsingFailure - Failure in parsing the config for the backup extension
 
 Error code: ExtensionConfigParsingFailure<br/>