Fix ERROR_PAGE_FAULT_COPY_ON_WRITE (0x2ED) – Demand Zero Fault

Common Cause #1: Corrupt or Misconfigured Page File

This error is infuriating, especially when it crashes a game or a big Excel workbook at the worst moment. The number one trigger I've seen in my years on the help desk is a damaged page file. Windows uses the page file as overflow for RAM, and when that file gets corrupted—often after a sudden power loss or a forced shutdown—it fails to handle copy-on-write operations correctly. Copy-on-write is a memory trick where processes share pages until one tries to write, then Windows makes a private copy. If the page file is wonky, that copy fails and boom: 0x2ED.

Here's the fix that works most of the time: delete and recreate the page file. Don't skip this part—it's the real solution, not just a band-aid.

1. Press Win+R, type sysdm.cpl, and hit Enter.
2. Go to Advanced tab → Settings under Performance.
3. Click the Advanced tab in the Performance Options, then hit Change under Virtual memory.
4. Uncheck Automatically manage paging file size for all drives.
5. Select your C: drive, choose No paging file, and click Set. A warning pops up—that's fine, click Yes.
6. Click OK and reboot. Windows will run without a page file for a bit.
7. After reboot, go back to the same spot: select C:, choose System managed size, click Set, then OK. Reboot again.

This forces Windows to rebuild the page file from scratch. I've fixed dozens of machines this way. If you're on an SSD, you might want to set a custom size (e.g., 4096–8192 MB) to prevent over-fragmentation, but system managed is fine for most.

Common Cause #2: Antivirus Interfering with Memory-Mapped Files

The second most common culprit is your security software. I know it sounds counterintuitive—antivirus is supposed to protect you, not crash your PC. But aggressive real-time scanning hooks into memory operations, and when it intercepts copy-on-write calls, it can misfire and produce a demand-zero fault. This is especially true with third-party AV like Norton, McAfee, or Bitdefender, but I've even seen Windows Defender cause it in rare cases.

You'll notice this error showing up when you open PDFs, run virtual machines, or compile code—anything that does heavy memory mapping.

How to test and fix

• Temporarily disable real-time protection. In Windows Defender, go to Virus & threat protection → Manage settings and flip real-time protection off. For third-party, right-click the tray icon and look for "Pause protection."
• If the error stops, re-enable protection and add exclusions for your most-used apps and folders. Right-click the AV icon → settings → exclusions. Add your game folders or project directories.
• If it still crashes, uninstall the third-party AV completely using the vendor's removal tool (e.g., Norton Removal Tool). Then rely on Windows Defender until you find a lighter option.

My opinion: skip the bloatware AV and just use Defender with controlled folder access. It's less prone to this kind of interference.

Common Cause #3: Outdated or Faulty Storage Driver

The third cause I run into is a driver issue. The page file lives on your disk, so if your storage controller driver (AHCI, NVMe, or RAID) is buggy, it can misread data and trigger a demand-zero fault. This often happens after a Windows update or if you're on a custom-built PC with a motherboard that's a few years old and the driver was never updated.

You'll notice this error more frequently when the system is under heavy I/O—like copying large files or running disk-intensive apps.

Fix it with these steps

1. Open Device Manager (Win+X → Device Manager).
2. Expand Storage controllers. Look for your device—e.g., "Standard SATA AHCI Controller" or "Intel(R) Chipset SATA/PCIe RST Premium Controller".
3. Right-click and choose Update driver → Search automatically.
4. If Windows says it's up to date, go to your manufacturer's site (Intel, AMD, or your motherboard vendor) and grab the latest chipset driver. Don't trust generic updates for this.

While you're in there, check for firmware updates for your SSD. Samsung and Western Digital have tools (Samsung Magician, WD Dashboard) that handle this. A stale SSD firmware can cause exactly this kind of page fault.

Quick-Reference Summary

I know this error is a pain, but it's fixable. Start with the page file—that's the highest hit rate—and work your way through. If none of these solve it, run sfc /scannow in an elevated Command Prompt and check for Windows updates, but that's rare. You've got this.