Fix STATUS_SECTION_NOT_EXTENDED (0xC0000087) in Windows

When you see STATUS_SECTION_NOT_EXTENDED (0xC0000087), it means Windows tried to map a file into memory and the address space couldn't be extended. In plain English: a program (or driver) ran out of room in virtual memory. The culprit here is almost always something locking the file or a corrupt pagefile.

I've seen this on Windows 10 and 11, mostly during startup or when launching a heavy app like Photoshop or a game. Sometimes it pops up right after a Windows update. Don't bother with reinstalling Windows — that's like burning down your house to fix a leaky faucet. Start with these fixes in order.

Cause #1: Antivirus is locking the file

Third-party antivirus (especially McAfee, Norton, or even some endpoint tools) can hold a lock on a file when it's being mapped. The system tries to extend the section, but the AV has it open, so you get 0xC0000087. This is the most common trigger I've seen in enterprise environments and home PCs alike.

Fix: Temporarily disable real-time protection, then try the operation that failed. If it works, the fix is to exclude your system drive from scans or switch to Windows Defender (which is actually decent now).

1. Open your AV dashboard.
2. Turn off real-time scanning (just for a few minutes).
3. Retry the app or command that errored.

If that clears it, add an exclusion for the affected file or folder. For example, if it's a game, exclude the game directory. If it's a driver, exclude C:\Windows\System32\drivers. But don't exclude your whole C: drive — that defeats the purpose.

Cause #2: Corrupted system files or drivers

When no AV is in play, the next suspect is a corrupted system file or a misbehaving driver. This happens after a botched update or a crash that left files in a weird state. The system can't extend the mapping because the file content doesn't match the metadata.

Fix: Run the System File Checker and DISM. Here's the command sequence — run them in an elevated command prompt (right-click CMD, run as admin):

sfc /scannow

Let that finish. If it finds errors and fixes them, great. If it doesn't, or throws a cryptic message, run DISM:

DISM /Online /Cleanup-Image /RestoreHealth

This repairs the Windows image itself. After it finishes, reboot and try again. SFC and DISM take 10-20 minutes, so grab a coffee.

Also check for bad drivers. Open Device Manager and look for any yellow exclamation marks. If you see one, update that driver. I've seen this error with old GPU drivers and some network adapter drivers. Get the latest from the manufacturer's site, not Windows Update.

Cause #3: Pagefile is too small or disabled

The mapped section needs virtual memory to extend into. If your pagefile is disabled or set to a fixed size that's too small, you'll hit this error under memory pressure. This is rarer but happens on systems with 8GB RAM or less, or when someone's "optimized" the pagefile off.

Fix: Let Windows manage the pagefile. Here's how:

1. Press Win + R, type sysdm.cpl, hit Enter.
2. Go to the Advanced tab → Settings under Performance.
3. Again the Advanced tab → Change under Virtual memory.
4. Check Automatically manage paging file size for all drives.
5. Click Set, then OK. Reboot.

Don't try to manually set a crazy big pagefile either — Windows knows better. If you're on a PC with 16GB+ RAM, you might think you don't need it. You do. Some apps expect it, and it's not just for RAM overflow.

Quick-reference summary

That's the short version. If none of those fixes it, you're looking at a deeper issue like failing RAM or a corrupted registry hive. But honestly, 90% of the time the AV is the problem. Uninstall it and use Defender — your machine will thank you.