QB Issue Resolution:

When installing QuickBooks or a product update, the following error occurs:

Error 1603: The update installer has encountered an internal error

MSI returned 1603: Fatal error during installation.

Why this is happening

This error can be caused by a damaged Microsoft Windows Installer file or a damaged QuickBooks installation.
How to fix it

Intuit recommends two solutions for this problem. The first solution may solve your problem, or you may need to try both to resolve the issue. For best results, perform the solutions in the order presented here.

Important: These troubleshooting steps may help resolve your issue. They focus on the Windows operating system, which is not an Intuit product. Intuit recommends if you are not comfortable doing these steps on your own, you can find expert assistance by consulting your computer’s manufacturer or a Windows expert. If the difficulty persists after performing these steps, contact your computer’s manufacturer or Microsoft.
Solution 1 (if you are installing QuickBooks)

Follow the steps in the Repair or reinstall .Net Framework article
Solution 2 (if you are updating QuickBooks)

Perform a Clean Install of QuickBooks and make sure to use a download of the program, and not a CD as the download will already be on the latest release.
Other Articles To Try

Error: MSI Returned 1603, installing QuickBooks
Error 1603: There was a problem installing Microsoft .NET Framework

Resolution for Issue 'Error 1603: The update installer has encountered an internal error.' available: Yes (Solved).
Source: Intuit Community forum.

Error 1603: The update installer has encountered an internal error.: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

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