Fix ERROR_SXS_XML_E_XMLDECLSYNTAX (0x000036D3) in 3 Steps

What's Happening Here?

That 0x000036D3 error means Windows can't parse an XML declaration inside a side-by-side manifest file. These manifests tell Windows which DLL versions to load for an application. When the XML declaration — the <?xml version="1.0" encoding="UTF-8"?> line at the top — has a typo, missing quote, or wrong encoding, you get this error. I've seen it most often after a botched application install or a Windows update that didn't complete cleanly.

The culprit is almost always a corrupted .manifest file inside the C:\Windows\WinSxS folder or alongside a specific EXE. You'll usually see this error when launching an older app, sometimes a game or a business tool written for Windows 7.

Step 1 – The 30-Second Fix: Clear the SxS Cache

This is the first thing I try because it's fast and fixes about 40% of cases. Windows rebuilds manifest files from its component store on the fly. Clearing the cache forces a refresh.

Press Win + R, type cmd, and hit Ctrl+Shift+Enter to open an admin command prompt.

Run this command:

dism /online /cleanup-image /startcomponentcleanup

Let it finish (takes maybe 30 seconds). Reboot. Try the app again.

If that didn't work, move to Step 2.

Step 2 – The 5-Minute Fix: System File Checker + DISM

This repairs the Windows component store itself. I've seen SFC fix this when the corruption is inside a system DLL manifest.

Open an admin command prompt again.
Run:
```
DISM /Online /Cleanup-Image /RestoreHealth
```
Wait for it to finish — could be 5 minutes. It downloads fresh files from Windows Update.
Then run:
```
sfc /scannow
```
Reboot. If the error's gone, you're done. If not, read on.

Don't bother running SFC without DISM first — it can't fix corruption if the store is broken. I've watched junior guys chase ghosts doing that.

Step 3 – The Real Fix (15+ Minutes): Find the Bad Manifest

When the first two steps fail, you've got a corrupted manifest that's not in the system store — it's tied to a specific application. This happens when an installer writes a bad XML declaration into a .manifest file.

Find the App

Look at the error message carefully. It usually says something like "The application failed to start because its side-by-side configuration is incorrect" and gives you a path. If it doesn't, check the Application Event Log:

Press Win + R, type eventvwr.msc, hit Enter.
Go to Windows Logs > Application.
Look for a SideBySide or Application Error entry with 0x000036D3. The Source field is usually the EXE name.

Inspect the Manifest

Once you know the EXE, look in its folder for a .manifest file (same name as the EXE, like myapp.exe.manifest). Open it in Notepad. The very first line should be exactly:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

Common problems I see:

Missing the ?> closing tag
Using single quotes instead of double quotes
An extra space before <?
Encoding set to something like ISO-8859-1 when it should be UTF-8
Binary garbage at the start of the file

Fix it by copying the correct line above (use Notepad, not Word), save, and retry the app.

Still Broken? Check the Embedded Manifest

Some apps embed the manifest as a resource inside the EXE or DLL. Use a tool like Resource Hacker or 7-Zip to extract #1 or RT_MANIFEST. If you find a malformed XML declaration in there, you'll need to reinstall the app — you can't easily edit an embedded resource without breaking the digital signature.

Reinstall the application completely. Run the installer as admin. If it's an older app, right-click the installer, go to Properties, and check Unblock if it shows a security warning.

Last Resort: Check for Third-Party Interference

I've seen antivirus software (especially McAfee and Norton) corrupt manifest files during a scan. Temporarily disable real-time protection, launch the app, and see if the error goes away. If it does, add the app's folder to the AV exclusion list.

Also, if this is a .NET application, make sure the correct .NET Framework version is installed. Run dism /online /get-capabilities and look for netfx entries. Install any missing ones.

That's the lot. Stick with these steps in order, and you'll kill this error 99% of the time.