Deferred Execution

• Unlike deferred execution actions, rollback execution actions launch only during rollback.
• Custom actions can only be sequenced between the InstallInitialize and InstallFinalize actions in execute sequence tables.
• Custom actions don’t have access to the Installation database.
• Custom actions can run both in the context of the user and elevated using the system context

Deferred execution in system context

• Like deferred execution actions, deferred-execution-in-system-context actions do not launch until the script that generated by the Windows Installer is run. However, actions of this type execute with no user impersonation.
• If the Custom action which installs or modify the system file directly should be run in “Deferred Execution in System Context”.
• Deferred custom actions must be made in system context if they need to make system changes that require elevated privileges