MSFS X won’t launch on new PC: side-by-side configuration is incorrect (0x3681)

Hi jjrenard44,

That “side-by-side configuration is incorrect” message is almost always Windows telling you a required Visual C++ runtime (or similar dependency) is missing/corrupted for FSX. On a brand new PC it’s very common, especially if you’re launching an older FSX install.

Step 1 – Confirm what Windows is complaining about (Event Viewer)
1) Press Windows Key and type Event Viewer
2) Go to:

• Windows Logs
• Application

3) Look for an Error at the exact time you tried to launch FSX (source often shows as SideBySide or similar).
4) Open it and look for the line that mentions something like Microsoft.VCxx.CRT and a version number.

If you can paste the text of that Event Viewer entry here (or at least the part mentioning VC runtime/version), it makes the fix very precise.

Step 2 – Verify you’re launching FSX “as installed,” not copied over
If you moved an FSX folder from the old PC to the new one (instead of doing a proper install), FSX can fail exactly like this because the required runtimes/assemblies aren’t registered on the new Windows install.

If that’s what happened, the cleanest route is:

• Install FSX from original media / installer on the new PC
• Then apply the same service packs / acceleration you had before
• Then add your add-ons back (one at a time)

Step 3 – Run the Windows side-by-side trace (sxstrace)
This is the tool Windows is pointing you at. It will spell out the missing component.

1) Open Command Prompt as Administrator
2) Run:

sxstrace Trace -logfile:sxstrace.etl

3) Now try launching FSX (let it fail with the same error)
4) Go back to the command prompt and stop tracing:

sxstrace StopTrace

5) Convert the trace to readable text:

sxstrace Parse -logfile:sxstrace.etl -outfile:sxstrace.txt

6) Open sxstrace.txt and paste the lines that mention:

• “Cannot resolve reference…”
• “ERROR: Cannot resolve…”
• Anything with VC / CRT / assembly version

Step 4 – Basic compatibility checks
These don’t usually fix side-by-side by themselves, but they’re worth doing once the runtime issue is sorted:

• Right-click fsx.exe → Run as administrator
• Try Compatibility mode (if you’re on Windows 11 especially)

Quick questions so I don’t steer you wrong
1) Which FSX do you have: FSX boxed, FSX: Steam Edition, or something else?
2) Did you install FSX fresh on the new PC, or did you copy it over from the old PC?
3) What Windows version is the new machine running (10 or 11)?
4) Can you paste the Event Viewer “SideBySide” error details (or the key lines from the sxstrace.txt)?

Once you drop that error text in, I can tell you exactly which runtime/component is missing and the least painful way to fix it.