You cannot access an installer session from a custom action that is not the current installation session. Custom actions are limited to working with only the active database of the session and no other databases. The following Windows Installer Database Functions must not be called from a custom action, because they require a handle to a database that is not the database of the current installation session:

MsiDatabaseMergeMsiCreateTransformSummaryInfo
MsiDatabaseApplyTransform
MsiDatabaseCommit
MsiDatabaseExport
MsiDatabaseGenerateTransform
MsiDatabaseImport
MsiEnableUIPreview
MsiGetDatabaseState

See Also

Accessing the Current Installer Session from Inside a Custom Action

Send comments about this topic to Microsoft

Build date: 8/13/2009