How do I fix FSX installation error 1628?

FSX installation error 1628 ("Failed to complete installation") means the legacy InstallShield setup for boxed Microsoft Flight Simulator X has stopped, usually because setup data is locked or corrupt, permissions are blocked, or the DVD cannot be read. On Windows 11, restart, clear %TEMP%, check the disc, then run the root setup.exe as administrator.

What does InstallShield error 1628 mean in Flight Simulator X?

InstallShield error 1628 is a final wrapper message rather than a diagnosis of one damaged FSX file. An earlier failure usually stopped the installer, after which InstallShield displayed 1628: Failed to complete installation.

This answer concerns Microsoft Flight Simulator X (FSX), especially the boxed Standard, Deluxe, Gold and Acceleration releases. The common mistake is applying boxed-DVD repairs to FSX: Steam Edition or a modern Microsoft Flight Simulator installation.

How do I fix 1628 failed to complete installation on Windows 11?

For boxed FSX on Windows 11, work through these steps in order and stop once the installer completes successfully.

1. Restart Windows. Use Restart rather than Shut down, because Windows Fast Startup can preserve part of the previous session. This closes abandoned setup processes and releases files held by an interrupted installation. Allow any pending Windows or application installation to finish before opening FSX setup again.
2. Clear the user temporary files. Press the Windows key and R, enter %TEMP%, and delete the contents Windows permits you to remove. If a file is reported as open in another program or in use, choose Skip; a few locked temporary files are normal. Delete the contents, not the Temp folder itself.
3. Check the system drive and Temp permissions. InstallShield extracts files to the Windows system drive even when FSX will be installed elsewhere, so that drive needs enough free space for temporary extraction. Confirm that you can create and delete a small test folder inside %TEMP%. If you cannot, test from a fresh local administrator account rather than changing folder ownership across Windows.
4. Test the FSX DVDs. Clean each disc from the centre outwards and inspect it for damage. As a read test, try copying its contents to a temporary folder; do not merge multiple discs or launch setup from Disc 2. A repeatable failure on the same cabinet file, a cyclic-redundancy message, Error 1305 or Error 1335 points to the disc or optical drive rather than InstallShield. Our guide to diagnosing FSX DVD read errors on Windows 11 covers that branch.
5. Remove only an incomplete installation entry. Open Windows 11's installed-apps list and uninstall the partial FSX component created by the failed attempt, if one exists, then restart. If Acceleration failed over a working base installation, remove only the incomplete Acceleration entry. Do not begin by deleting a working FSX folder or its Windows Installer records.
6. Reset the legacy InstallShield folder. Do this only when the exact 1628 message came from boxed FSX or another trusted legacy installer. With all installers closed, rename C:\Program Files (x86)\Common Files\InstallShield to a backup name such as InstallShield.old. If that path is absent, check C:\Program Files\Common Files\InstallShield; if neither exists, skip the step. Renaming is reversible and safer than deletion. Do not alter C:\Windows\Installer.
7. Run the correct setup program. Right-click setup.exe in the root of the first FSX DVD and select Run as administrator. Do not launch an individual MSI or a setup file buried inside a cabinet folder. For a two-disc FSX installation, start with Disc 1 and insert Disc 2 only when the running installer requests it.
8. Keep the Gold installation order intact. For FSX Gold, install the base Deluxe edition from its discs, launch FSX once and complete activation, then install Acceleration. Do not begin with the Acceleration disc or mix standalone service packs into the Gold sequence. We cover the disc order and related InstallShield failures in our boxed FSX Gold installation checklist.
9. Try a clean Windows start if software is interfering. Open System Configuration, hide all Microsoft services, disable the remaining third-party services and startup applications, restart, and run the trusted FSX setup. Restore normal startup afterwards. Choose this route when the failure affects every Windows account; use a fresh local administrator account instead when it occurs in only one profile.

Does the same 1628 fix apply to FSX: Steam Edition?

No: Steam's own installation failures should be repaired through Steam, while an exact InstallShield 1628 pop-up usually belongs to a separate prerequisite or add-on.

• Steam reports a download or installation failure: restart Windows and Steam, then use Steam's file-verification command for FSX: Steam Edition. Clear Steam's download cache only when the download stage repeatedly stalls or restarts.
• A separate setup window reports 1628: identify the aircraft, scenery, utility or prerequisite named in that window and apply the temporary-file and InstallShield steps to that installer.
• Do not mix editions: boxed FSX discs, Acceleration and standalone boxed service packs are not repair tools for FSX: Steam Edition.

What if an aircraft or scenery installer shows error 1628?

An add-on installer displaying 1628 has failed independently and does not prove that the main FSX installation is corrupt. Close FSX and related utilities, extract the complete downloaded archive to an ordinary local folder, and run the trusted setup from there rather than from inside the compressed archive.

If the installer asks for a destination, verify which edition it supports and select the actual simulator directory. The boxed and Steam paths often differ, so use our instructions to locate the correct FSX or Steam Edition installation folder instead of guessing.

What if Windows says a file is open in another program?

A file reported as open in another program is locked by a running process and should not be forcibly deleted. When clearing %TEMP%, skip that file and continue; the folder does not have to be completely empty for FSX setup to work.

If the message prevents you from renaming the InstallShield folder, restart Windows and try the rename before opening Steam, FSX or another installer. If it remains locked, use the clean-start method above. Do not terminate unfamiliar Windows services or install file-unlocking utilities merely to remove temporary setup data.

What should I check if error 1628 still appears?

The useful cause is often recorded immediately before the closing 1628 line. After the failure, open %TEMP%, sort by modification time and inspect the newest setup or InstallShield log. Log names vary, so look for the first error rather than searching only for 1628.

If the DVD cannot be read consistently, software repairs will not make its data reliable. Avoid modified setup executables, replacement DLL downloads and files taken from an unknown disc image; they can introduce a second problem while leaving the original media fault unresolved.

Should I use compatibility mode or a registry cleaner?

Compatibility mode is a final diagnostic test, not the main fix for FSX error 1628. It cannot repair unreadable media, locked temporary files or a damaged InstallShield engine. If the earlier steps fail, apply Windows' compatibility troubleshooter only to the DVD's root setup.exe, not to Steam, an MSI file or the installed simulator executable.

Do not use a registry cleaner, delete Windows Installer records, remove the entire Common Files directory or download replacement system DLLs. Those actions can leave FSX in a state where it neither installs nor uninstalls, turning a recoverable 1628 failure into a broader Windows Installer problem.