Fix Error 1720 Windows Installer Package Problem

Error 1720, “There is a problem with this Windows Installer package,” stops a program from installing or uninstalling on Windows. The fix is usually to run the installer as an administrator, clear the Windows Installer cache, or repair the Windows Installer service itself. Below are the step-by-step fixes, what causes the error, and how to avoid it in the future.

What Causes Error 1720

Error 1720 appears when the Windows Installer engine (msiexec.exe) cannot complete an operation on an .msi or .msp file. The message often continues with “A script required for this install to complete could not be run.” That script is typically a custom action written in VBScript or JScript that the installer package calls during setup. Common triggers include:

• Corrupted installer cache – Windows stores a copy of every installed .msi in C:\Windows\Installer. If that file is damaged or missing, the installer cannot run its scripts.
• Broken Windows Installer service – The service may be disabled, stopped, or its registry entries corrupted.
• Insufficient permissions – The install is trying to write to Program Files or the registry without admin rights.
• Antivirus interference – Security software can block the script engine or the temporary files the installer creates.
• Corrupted script engine – If Windows Script Host (WSH) is damaged or disabled, the VBScript/JScript custom action cannot run.

Most error 1720 reports occur with older programs, especially those written for Windows XP or Vista, but it can happen with any .msi package.

How Windows Installer Works

Windows Installer is a service that manages software installation, repair, and removal. Every .msi file is a database that contains the files, registry keys, shortcuts, and a sequence of actions. Some actions are built-in (copying files, writing registry), but many packages include custom actions – small scripts or executables that run at specific points, like after files are copied or before the shortcut is created. Error 1720 specifically means the installer reached one of those custom action steps and the script failed to execute.

The installer also maintains a cache in C:\Windows\Installer. When you install a program, the .msi is copied there so Windows can later repair, update, or uninstall it. If that cached file gets corrupted (for example, by a disk error or a failed update), the installer cannot read the script instructions and throws 1720.

Fix 1: Run as Administrator

The simplest and most common fix. Right-click the installer file (usually named something like setup.exe or program.msi) and select Run as administrator. If you are installing from a CD or a downloaded folder, also make sure the file is not blocked. Right-click the file, choose Properties, and if you see an Unblock checkbox at the bottom, tick it and click OK.

If the error appears during an uninstall, go to Control Panel > Programs > Programs and Features, right-click the program, and choose Uninstall – but first try running the uninstaller as administrator from the Start menu shortcut if one exists.

Fix 2: Repair the Windows Installer Service

If running as admin does not help, the service itself may be damaged. Open an elevated Command Prompt (search for cmd, right-click, Run as administrator) and run:

1. msiexec /unregister
2. msiexec /regserver

This re-registers the Windows Installer engine. Then restart the service: open Services (type services.msc in Run), find Windows Installer, right-click and choose Restart (if it is not running, set Startup type to Manual and click Start).

If the service is missing entirely, you may need to run the System File Checker:

1. Open Command Prompt as administrator.
2. Type sfc /scannow and press Enter.
3. Wait for the scan to complete (may take 10-20 minutes).
4. Restart your PC and try the install again.

Fix 3: Clear the Installer Cache (Carefully)

The C:\Windows\Installer folder can become bloated or corrupted. Deleting files from it is risky because it can break uninstalls for other programs. A safer approach is to use the Program Install and Uninstall Troubleshooter from Microsoft, which scans for corrupted installer registry entries and repairs them.

If you are comfortable with advanced steps, you can identify the specific .msi for the problem program. Open the installer file with a tool like Less MSIérables or use the Windows Installer CleanUp Utility (no longer officially supported but still available from third-party archives – use at your own risk). A cleaner method is to re-download the installer from the vendor and save it to a fresh folder, then run it. This bypasses the cached copy entirely.

Fix 4: Check Script Host and Antivirus

Since error 1720 is about a script, ensure Windows Script Host is enabled. Open Control Panel > Programs > Turn Windows features on or off (or search for Windows Features). Look for Windows Script Host under the .NET Framework or Scripting section – make sure it is checked. If it is unchecked, tick it, click OK, restart, and try again.

Temporarily disable your antivirus (or add an exclusion for the installer folder and the temp folder) and then run the install. Some security suites block the script engine from executing, which triggers 1720. Remember to re-enable the antivirus after the install.

Fix 5: Use the Windows Installer CleanUp Utility or Reboot

If a previous install left a partial state, a reboot can clear the temporary files and reset the installer service. After rebooting, try the install again. If it still fails, download the Microsoft Program Install and Uninstall Troubleshooter (available from Microsoft’s support site) and run it. It will detect and fix common installer problems, including corrupted registry keys that cause 1720.

For stubborn cases, you can also try installing in a clean boot state – disable all non-Microsoft startup items and services using msconfig (System Configuration), restart, and attempt the install. This isolates any third-party software conflict.

Frequently Asked Questions

Can I ignore error 1720 and continue?

No. The install will abort, and the program will be partially installed or not installed at all. You may also end up with broken registry entries that cause problems later. Fix the underlying issue before proceeding.

Does error 1720 mean the installer file is corrupted?

Not necessarily. It means the installer could not run a script, which can be due to permissions, service issues, or antivirus. However, a corrupted download is one possible cause, so re-downloading the installer is a reasonable first test.

Will this error damage my computer?

No, error 1720 itself is not harmful. It is a warning that the installation failed. The only risk is if you try to force the install by manually copying files, which can leave the system in an inconsistent state. Always fix the installer properly.

Does this error happen on Windows 10 and Windows 11?

Yes, it can occur on any modern Windows version, though it is more common with older software. The fixes above work on Windows 7, 8, 10, and 11.

What if none of these fixes work?

If you have tried all the steps and the error persists, the installer package may be incompatible with your Windows version, or the vendor may have a specific patch. Contact the software vendor’s support or check their website for an updated installer. You can also try running the installer in compatibility mode – right-click the file, choose Properties > Compatibility, and select an older Windows version like Windows 7.

Is it safe to delete the Windows Installer cache?

No. Deleting files from C:\Windows\Installer can break the ability to uninstall or repair other programs. Only use the official Microsoft troubleshooter or the vendor’s own cleanup tool. If you must manually remove a file, back it up first and only remove the one related to the problem program.

Related

• Windows Update Error: PC Turned Off? Fix It
• How to Watch Netflix on Zoom: Easy Steps
• iOS 11 Compatible Devices: Full List & Install Guide