0x000003E7 ERROR_SWAPERROR Fix: Page File Crash

Quick Answer (for advanced users)

Disable the page file, reboot, run chkdsk c: /f /r from an admin command prompt, re-enable page file set to 1.5x RAM.

What Actually Happens Here

Windows uses a file called pagefile.sys on your system drive (usually C:) as overflow memory when RAM gets full. The error 0x000003E7 (which is decimal 999, named ERROR_SWAPERROR) pops up when Windows tries to swap data between RAM and this file but the operation fails partway through. The reason step 3 works is that the page file lives on the disk, so any bad sector or file system corruption on that drive kills the swap operation instantly.

I've seen this most often on laptops with aging 5400 RPM HDDs—they develop bad sectors over time, and the page file happens to sit right on one. Also happens when the system drive has less than 5% free space, because Windows needs room to expand the page file dynamically.

Fix Steps (in order)

Free up disk space. Delete temp files, empty Recycle Bin. You need at least 10% free space on the drive that holds the page file. Open File Explorer, right-click C:, go to Properties, and check the free space. If it's below 10%, run Disk Cleanup (search for it in Start menu) and let it clear everything.
Check the disk for errors. Open Command Prompt as Administrator (right-click Start > Command Prompt (Admin) or Windows Terminal (Admin)). Run:
```
chkdsk c: /f /r
```
It'll ask to schedule on next reboot—type Y and restart. This scans the whole disk surface and fixes bad sectors. Expect it to take 1–4 hours on a mechanical drive.
Reset the page file. Go to System Properties (search for 'advanced system settings' in Start). Under Performance, click Settings. Go to the Advanced tab, under Virtual memory click Change. Uncheck 'Automatically manage paging file size', select C:, choose 'No paging file', click Set. Reboot. Then go back, select C:, choose 'System managed size', click Set, reboot again. This forces Windows to create a fresh page file on clean sectors.
Check RAM stability. Run Windows Memory Diagnostic (search in Start) and let it run on restart. A full pass takes 30–60 minutes. If it finds errors, you need to replace a stick of RAM. Bad RAM can corrupt the page file even if the disk is fine.
Update storage drivers. Open Device Manager (right-click Start > Device Manager). Expand 'Storage Controllers'. Right-click the SATA or NVMe controller, choose Update driver > Search automatically. Reboot after.

Alternative Fixes (if main steps fail)

Move page file to another drive. If you have a second physical drive, disable page file on C:, set it on D: (or whichever) with 'System managed size'. This bypasses bad sectors on the system drive entirely.
Run SFC and DISM. Corrupted system files can cause swap failures. Open admin command prompt and run:
```
sfc /scannow
```
Then:
```
DISM /Online /Cleanup-Image /RestoreHealth
```
Reboot after both finish.
Check for overlay software. Some encryption or backup tools (e.g., BitLocker, some third-party antivirus) hook into the page file. Temporarily disable them to see if the error stops.

Prevention Tip

Keep at least 10% free space on your system drive always. On SSDs, run chkdsk every few months (it tells the drive to reallocate bad blocks). On HDDs older than 3 years, consider replacing it before it fails completely—this error is often the first sign of a dying disk, not just a software glitch.

Spoken from experience: I've fixed about a dozen machines with this exact error. Nine of them had a near-dead hard drive that passed a quick SMART check but failed during deep scan. The other three just needed the page file reset. Don't skip the chkdsk step—it's where the real fix lives.