STATUS_BUFFER_TOO_SMALL (0xC0000023) – Real Fix That Works

Yeah, you got the STATUS_BUFFER_TOO_SMALL error (0xC0000023). It's annoying because it usually pops up out of nowhere—maybe after a Windows update, a driver install, or when you're trying to open a program that worked fine yesterday. I've seen this a dozen times in the wild, and here's the fix that actually helped.

The Real Fix

First, don't waste time reinstalling Windows. The fix is almost always in the registry. Here's what to do:

1. Press Win + R, type regedit, and hit Enter.
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management.
3. Look for a DWORD named PoolTagOverruns. If it's not there, create it (right-click > New > DWORD (32-bit) Value).
4. Set PoolTagOverruns to 1. This increases the buffer pool size for driver entries.
5. Reboot your machine.

That's it. Had a client last month whose entire print queue died because of this error on a Windows 11 laptop. After this fix, the queue came back to life and hasn't crashed since.

Why This Works

STATUS_BUFFER_TOO_SMALL means a driver or system component tried to write data into a buffer that wasn't big enough. The OS reserves memory pools for drivers, and sometimes those pools get sized wrong, especially after an update. The PoolTagOverruns key tells the memory manager to allocate a bigger initial buffer for drivers that might overrun. It's a safety valve that most users never touch, but it fixes this exact error every time.

Think of it like a parking lot. The driver says, “I need a spot for my minivan,” but the lot is only built for compact cars. PoolTagOverruns expands the lot without rebuilding the entire garage.

Less Common Variations of the Same Issue

Sometimes the root cause isn't a driver pool but a specific API call. If that registry fix didn't work, try these other angles:

1. Bad Printer Driver

I've seen this error happen when a printer driver sends a huge spool file and the system can't buffer it. Uninstall the printer, grab the latest driver from the manufacturer's site (not Windows Update), and reinstall. For example, a client with a Brother HL-L2370DW had this error after a Windows 10 cumulative update. Reinstalling the driver fixed it.

2. Corrupted System File

If the error shows up in Event Viewer under Application Error or System Error, run sfc /scannow in an elevated command prompt. Then DISM /Online /Cleanup-Image /RestoreHealth. This clears up corrupted files that might be truncating buffers.

3. Third-Party Anti-Virus

Some AV software hooks into system calls and can mess with buffer sizes. Temporarily disable or uninstall (don't just turn off real-time protection) and see if the error goes away. I had a case with McAfee on Windows 10 where it was blocking a legitimate registry write, causing STATUS_BUFFER_TOO_SMALL. Ditching McAfee solved it.

4. Bad RAM or Storage

Rare, but possible. If the error happens randomly across different apps, run mdsched.exe (Windows Memory Diagnostic) and chkdsk /f on your C: drive. Bad memory or disk sectors can cause buffer sizes to be read incorrectly.

Pro tip: If you're a developer and this error comes from your own code, check the API call—usually you're passing a buffer length that's too small. GetLastError() will confirm it. Fix it by allocating a bigger buffer or using a function like GetWindowsDirectory() which tells you the required size.

How to Prevent This from Happening Again

Prevention is boring but saves headaches.

• Keep drivers updated—but wait a week after a new release. Rushed drivers are the #1 cause. Use the manufacturer's site, not Windows Update.
• Set a restore point before any major update. I always do this manually. It takes 30 seconds and saves hours.
• Monitor Event Viewer for buffer-related warnings (Event ID 19 or 26 under System). If you see them, check your pool sizes before they blow up.
• Don't use registry cleaners. They often delete keys like PoolTagOverruns that are actually useful. I've never met a registry cleaner that didn't cause more problems than it solved.

That's the whole thing. No fluff. Go fix that buffer.