Installer error 1603: "A fatal error occurred during installation" and how to fix it

Published Sources checked By helps.wiki editorial team

Error 1603 is the generic Windows Installer code for "something failed fatally, so the install was rolled back." It is a catch-all, so the fix depends on the cause. Start with the quick checks (already installed, folder and drive choice, SYSTEM permissions), then read a verbose log to find the real culprit.

Applies to:Windows 10all editionsWindows 11Windows Server
On this page

What it means

Error 1603 comes from Windows Installer, the service that handles MSI packages. Its official name is ERROR_INSTALL_FAILURE. The message says a fatal error happened during installation, and when you click OK the installer undoes whatever it had already done.

The code does not name a specific fault. It is a catch-all, and the same number can come from very different problems. Managed deployment tools such as Configuration Manager, Patch My PC or Intune report it as "exit code 1603".

The fixes below go from the quick checks Microsoft documents to reading the installer log, which is the only reliable way to see what actually broke. Microsoft's article was written around Windows 10, but the error can hit any MSI-based installer on any Windows version.

Symptoms and causes

You are likely dealing with this problem if:

  • A dialog reads "Error 1603: A fatal error occurred during installation." After you click OK, the install rolls back.
  • A silent or managed deployment reports only "exit code 1603".

The usual causes, most common first:

A custom action in the package failed
Advanced Installer, which makes installer-authoring software, calls this the most frequent trigger. Most real-world cases are product-specific, and only the log reveals them.
The app is already installed, or partly installed
Microsoft lists an existing or leftover installation as a cause. It can happen after a Windows upgrade.
The SYSTEM account lacks Full Control of the target location
Windows Installer does its work as SYSTEM, so it needs Full Control on the destination folder or drive.
The target folder is encrypted
Installing into a folder protected with EFS encryption can cause 1603 (Microsoft, Advanced Installer).
The target drive is a substitute drive
A drive letter created with the subst command is a known cause according to Microsoft.
Other environmental problems
Advanced Installer and Patch My PC also list insufficient user permissions, disabled 8.3 short file name creation, antivirus interference, a corrupted installer package, a web installer blocked by a firewall or network, low disk space, the app running during install, and installing from a network path.

How to fix it

Work through these in order. They start with the quickest, safest checks and move to deeper repairs; stop as soon as the problem is gone.

1.Check whether the app is already installed

Easy

A leftover or existing copy is one of the causes Microsoft documents, and removing it is quick.

  1. Open Settings and go to the Apps page (it is labelled Apps & features in Microsoft's article; the exact menu names vary by Windows version). Look for the program.
  2. If it is listed, select it and choose Uninstall.
  3. Restart the installer and try again.

2.Install to a different location

Easy

Encrypted folders, subst drives and network paths are known to trigger 1603.

  1. When the installer asks for a destination, pick a normal local folder that is not encrypted.
  2. Avoid any drive letter created with subst, and avoid network paths. A local drive is the safe choice.
  3. Run the installer again.

3.Run the basic hygiene checks

Easy

Advanced Installer and Patch My PC list these as common triggers, although Microsoft does not mention them.

Before you start: If you turn off third-party antivirus for the test, turn it back on straight afterwards, whatever the result.

  1. Right-click the installer and choose Run as administrator.
  2. Close the target app if it is running, and close other programs in the background.
  3. Make sure the drive has enough free space.
  4. If you suspect a third-party antivirus, pause it briefly, run the installer once, then re-enable it.

4.Give the SYSTEM account Full Control

ModerateChanges settings

Windows Installer runs as SYSTEM. If SYSTEM cannot write to the install location, the install fails with 1603. SYSTEM normally already has Full Control on local drives such as C:, so this fix mainly applies to non-system or data drives where permissions were changed or never set up that way.

Before you start: Changing permissions on a whole drive can be slow and can disturb inherited permissions. Check the specific destination folder first, and only touch the drive if the folder is not enough. Note the original settings before you change anything, and create a restore point first.

  1. Start with the destination folder: right-click it in File Explorer, choose Properties, open the Security tab and check whether SYSTEM is listed with Full control allowed. If it is, this is not your cause.
  2. If the folder is fine and you are installing to another drive, right-click that drive and choose Properties, then open the Security tab.
  3. If SYSTEM is not in the list, click Edit > Add, type SYSTEM, click Check names, then OK.
  4. Select SYSTEM and make sure Full control is set to Allow.
  5. Go to Advanced > Change permissions, select the SYSTEM entry and click Edit.
  6. Set Applies to to "This folder, subfolders and files", then confirm.
  7. Wait for the permissions to propagate, then run the installer again.

5.Capture a verbose log and find the failing step

Advanced

Since 1603 is generic, the log is the only way to learn what really failed. It works for MSI packages.

  1. Open a Command Prompt or PowerShell window and run the installer with logging turned on. Replace the paths with your own.
    Command Promptrun as administrator
    msiexec.exe /i "C:\path\example.msi" /L*V "C:\package.log"
  2. Open C:\package.log in a text editor and search for Return value 3. Advanced Installer describes this as the marker of a failed action.
  3. Read the lines just above that match. They name the action or condition that failed, such as a permission problem, a missing file or a blocked step.
  4. Fix the condition the log reports. If the failure is inside the package itself, send the log to the software vendor, since they would need to correct the custom action.

Check that it worked

  • The installer finishes without the 1603 dialog and the program appears in your installed apps list.
  • In a managed deployment, the exit code is 0 and the app shows as installed.
  • The program starts normally.

If it still fails

  • Keep the verbose log and read it carefully. Most stubborn 1603 cases are product-specific, and the log line above Return value 3 points to the cause.
  • Send that log to the vendor of the software. Products such as Java, Adobe apps, SQL Server and .NET can have their own 1603 causes, so check the vendor's support pages.
  • A different installer error with a similar rollback pattern is covered in Installer error 2503. For Epic Games, see EOS-ERR-1603.

Questions

Windows Update shows 0x80070643. Is that the same as 1603?

Not necessarily. 0x80070643 is a generic fatal-error code that can appear for several kinds of install failures, so do not assume it is 1603. If it appeared while an MSI package was installing, the installer log is still where the real cause is found.

Sources

  1. MSI installation error 1603 - Windows ServerOfficial · Microsoft Learn
  2. msiexecOfficial · Microsoft Learn
  3. How to Troubleshoot MSI Error 1603: Fatal Error During Installation · Advanced Installer (Caphyon)
  4. Installation fails with error code 1603 · Patch My PC

Browse