Fix 0x000036F5 Manifest XML Case Error

What's Actually Happening

The XML parser in Windows Side-by-Side (SxS) is strict about case. The reserved name xml must always be lowercase — no XML or Xml. When a manifest or config file has <XML> or <?XML version="1.0"?>, you get error 0x000036F5. This usually shows up when installing a program, launching an app, or during Windows Update.

I've seen this with old installers from 2010-era software and badly hand-edited XML files. Sometimes it's a corrupted registry entry. The culprit is almost always a file named app.manifest or *.config that someone touched with Notepad and didn't respect case.

Fix 1: The 30-Second Registry Tweak

If you're lucky, the error comes from a broken registry key. Let's try the quick fix first.

Press Win + R, type regedit, hit Enter.
Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SideBySide. If it doesn't exist, create it.
Right-click on the right pane, choose New > DWORD (32-bit) Value.
Name it PreferExternalManifest and set it to 1.
Reboot and try the failing install again.

This tells Windows to look for external manifests instead of embedded ones. It won't fix a genuinely malformed file, but it bypasses some bad registry references. Don't bother with this if the error is tied to a specific app you just downloaded — it's a band-aid, not a cure.

Fix 2: The 5-Minute Manifest Edit

If the registry trick didn't work, there's a bad XML file on your system. Here's how to find it.

Check the application folder. Look for files named YouApp.exe.manifest or app.config. Open them in Notepad++ or VS Code (not regular Notepad — you need to see encoding).
Search for any occurrence of XML or Xml that should be xml. The most common spots: <?xml version="1.0" encoding="UTF-8"?> — the xml after ? must be lowercase. Also check for <XML...> anywhere in the file.
Fix each case. Save the file as UTF-8 with BOM if it's for a 32-bit app, otherwise plain UTF-8.

Here's a typical broken line:

<?XML version="1.0" encoding="UTF-8"?>

The correct version:

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

Also check attribute names. An attribute like XmlNamespace might need to be xmlns — that's a common gotcha. The XML spec reserves xml only, but namespaces starting with xml are also case-sensitive.

Fix 3: The 15-Minute Deep Dive

When the above fails, the problem is likely in Windows component store. Use DISM to scan and repair.

Open Command Prompt as Administrator.
Run sfc /scannow — this checks system file integrity. Takes 5-10 minutes.
If SFC finds nothing, run DISM /Online /Cleanup-Image /RestoreHealth. This fixes component store corruption.
Reboot and retry the install.

If you know which application triggered the error, uninstall it completely first. Look in Program Files and Program Files (x86) for stray manifest files. Sometimes leftover files from a failed uninstall cause this.

One more thing: check the application's event log. Press Win + X, select Event Viewer, go to Windows Logs > Application. Look for a warning with the same error code. The message often tells you the exact file path. That saves you from guessing.

If Nothing Works

For a system-wide issue, a repair install of Windows might be your only option. But try the steps above first. In my experience, 90% of the time it's a single malformed manifest file. Fix that, and the error disappears.

Remember: XML is case-sensitive. XML is not xml. The Windows parser follows the spec — it's not being picky just to annoy you.