When a backup job starts, Veeam Backup & Replication connects to the Veeam Agent machine to initiate the backup process. The connection is based on Windows API and uses RPC and WMI queries. If Microsoft Windows is low on desktop heap memory for services running under LocalSystem account, Microsoft Windows can reject the incoming queries. As a result, the following message will be displayed in System Event Log (eventvwr.msc) of the Veeam Agent machine:
Log Name: System
Event ID: 243
Task Category: None
A desktop heap allocation failed.
DCOM errors (Event ID 10010) can be found in System Event Log of the Veeam Agent machine too.