Error 1935 Installing Visual C++ 2005 for FSX: Windows Blocked the Installer From Its Own WinSxS Folder, and Four Commands Unblock It

Error 1935 means the Visual C++ installer asked Windows to register an assembly in C:\Windows\WinSxS and Windows refused. On a modern PC that comes down to three things: the component store has a broken entry, the Windows Modules Installer service is off, or a Windows update is half-finished and waiting on a reboot. FSX: Steam Edition is from 2006 under the hood and needs the 2005 runtime, both 32-bit and 64-bit, so the game won't start until this installs. The steps below repair the store, start the service, then install the runtime from the copy Steam already downloaded. Most people are flying after step 3.

First Check Whether the Runtime Is Already There

Steam’s first-time setup reruns the installer on every machine, and some PCs already have the runtime from another game. Open PowerShell and ask Windows what’s installed:

Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*,
                 HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\* |
  Where-Object DisplayName -like "Microsoft Visual C++ 2005*" |
  Select-Object DisplayName, DisplayVersion | Sort-Object DisplayName

DisplayName                                                  DisplayVersion
-----------                                                  --------------
Microsoft Visual C++ 2005 Redistributable                    8.0.61001
Microsoft Visual C++ 2005 Redistributable (x64)              8.0.61000

• Both lines present: the runtime is fine. Skip to the last section and make Steam stop retrying.
• Only the first line: the 64-bit half is missing. That’s the one your dialog is about. Carry on.
• Nothing at all: carry on. Both halves will install together in Step 3.

Repair the Component Store With DISM and SFC

Open Command Prompt as administrator (press Win, type cmd, right-click, Run as administrator). Run these four one at a time. The third one can take 20 minutes and sits at 62% for most of it. That’s normal.

DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

The restore operation completed successfully.
...
Windows Resource Protection found corrupt files and successfully repaired them.

• If RestoreHealth reports Error: 0x800f081f, it couldn’t fetch replacement files from Windows Update. Plug in an ethernet cable or wait and retry. It needs the internet.
• Reboot after SFC even if it says nothing was found.

Turn the Windows Modules Installer Service Back On

This service (its real name is TrustedInstaller) is the only account allowed to write into WinSxS. Debloat scripts and some “gaming optimizer” tools disable it to stop Windows Update, and from that moment every installer that touches WinSxS fails with 1935.

sc config TrustedInstaller start= demand
sc start TrustedInstaller
sc query TrustedInstaller

STATE              : 4  RUNNING

While you’re there, check nothing is waiting on a reboot. A half-finished Windows update locks the store until the PC restarts:

Test-Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\RebootPending"
Test-Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired"

False
False

Install Both Halves From the Copy Steam Already Downloaded

Steam put the installers in the game folder. Run them from there, as administrator, with a log file so you can see the real reason if it fails again. The 2005 installer is a wrapper around an MSI, so /l*v works as it does on any MSI.

cd /d "C:\Program Files (x86)\Steam\steamapps\common\FSX\_CommonRedist\vcredist\2005"
vcredist_x86.exe /q /l*v "%TEMP%\vc2005_x86.log"
vcredist_x64.exe /q /l*v "%TEMP%\vc2005_x64.log"

• Steam on another drive? Right-click FSX in your Library → Manage → Browse local files and go up one level into _CommonRedist.
• /q runs it silently. If a dialog pops up anyway, that’s the error again, and the log has the detail.
• Rerun the PowerShell check from the top. Both lines should now be present.

If Steam’s Copy Is Missing or Damaged

Download Microsoft’s own build. You want the Visual C++ 2005 SP1 Redistributable MFC Security Update (KB2538242), which is the 8.0.50727.6195 version named in your dialog. It’s on the Microsoft Download Center as two files, vcredist_x86.EXE and vcredist_x64.EXE. Install the x86 one first, then x64.

Read the HRESULT in the Log When It Still Fails

The dialog hides the useful number. The log doesn’t. Search it for 1935:

Select-String -Path "$env:TEMP\vc2005_x64.log" -Pattern "1935" | Select-Object -First 3

MSI (s) (A4:58) [15:12:03:721]: Product: Microsoft Visual C++ 2005 Redistributable (x64) -- Error 1935.
An error occurred during the installation of assembly 'Microsoft.VC80.MFC,...'. HRESULT: 0x800736B3.

Get FSX Past First-Time Setup Once the Runtime Is In

Steam marks the redistributable as installed per game, so after a failed attempt it tries again every launch. With both lines present in the PowerShell check, launch FSX from the Library. The first-time setup runs through in a few seconds this time. If it still throws 1935, verify the game files so Steam replaces the installer it has:

1. Library → right-click Microsoft Flight Simulator X: Steam Edition → Properties.
2. Installed Files → Verify integrity of game files.
3. Launch again.

And if the game then opens to a “side-by-side configuration is incorrect” message, that’s the other half of the same story: the x86 runtime is missing, since FSX itself is a 32-bit program. Run vcredist_x86.exe from Step 3 and it starts.

What Doesn’t Fix It, Even Though Guides Say So

• The RegistrySizeLimit tweak. That was a real fix on Windows XP and Vista, where the registry had a hard size cap. Windows 10 and 11 don’t have the cap. Changing the value does nothing.
• Uninstalling .NET Framework. Error 1935 on .NET installs comes from the same store, but the VC++ 2005 runtime doesn’t use .NET. Leave it alone.
• Downloading “Visual C++ 2005” from a random mirror. Half the links in old forum threads are dead and the other half are the 2005 RTM build without the security update. Use Steam’s copy or Microsoft’s KB2538242 page.