InstallExecuteSequence vs InstallUISequence Table for MSI Installers
Understanding how actions are sequenced when building or customizing Windows Installer (MSI) packages is essential.
Many tables can influence the MSI installation behavior, but the InstallExecuteSequence and InstallUISequence tables are among the most important.
These tables define the circumstances and times when installer actions apply. Although they may look similar, they serve very different purposes.
What is InstallUISequence?
The InstallUISequence table controls the actions that run during the user interface phase of an installation.
This is the first phase the user experiences when launching an MSI with a full UI.
Its primary purpose is to collect user input and prepare information that the installer needs later during installation.
You can use the InstallUISequence table to manage dialogs, user prompts, license agreements, installation options, and other interface-related actions.
The InstallUISequence table only runs its actions in full UI, not in silent mode (/qn) or basic UI (/qb or LIMITUI=1).
What is InstallExecuteSequence?
The InstallExecuteSequence table controls the actions that occur during the execution phase of the installation, which modifies the system.
The InstallExecuteSequence table runs its actions in full UI, basic UI (/qb or LIMITUI=1), and in silent mode (/qn). This table is important for enterprise silent deployments in environments using MECM (SCCM) and Intune.
Most system-changing custom actions must run as deferred actions. These actions run in the privileged execution context during the InstallExecuteSequence process.
For more details about deferred custom actions, you can check out our article here.
Key Differences between InstallUISequence and InstallExecuteSequence
Feature | InstallUISequence | InstallExecuteSequence |
|---|---|---|
Runs in silent mode | ❌No | ✅Yes |
Runs in basic UI mode | ❌No | ✅Yes |
Run in full UI mode | ✅Yes | ✅Yes |
Performs System Changes | ❌No | ✅Yes |
Typical use | User interaction, UI logic | System modifications, deferred custom actions |
Final Takeaways
- You need to learn how Windows Installer sequences actions because these tables dictate the entire MSI flow, from the first dialog to the last system change.
- The InstallUISequence table takes place in the user interaction phase and runs only when the installer displays a full UI.
- The InstallExecuteSequence table runs in the execution phase and carries out system modifications in every UI level, including silent mode, making it important for enterprise deployments.
- Most system-modifying custom actions must run as deferred actions in the InstallExecuteSequence process so that they can execute with the correct privileges.
Conclusion
The InstallUISequence and InstallExecuteSequence tables are essential components of MSI packages.
Knowing where to place actions can prevent installation failures, silent-mode issues, permission problems, and rollback inconsistencies.
Written by
Horatiu Vladasel
Horatiu is a Software Packager/Sequencer with over 10 years experience, who has worked as a Software Packager at IBM and is currently offering software packaging services to companies such as BT or Nationwide.