Quick Answer
For advanced users: Disable DDC/CI on your monitor's OSD or update your graphics driver (NVIDIA or AMD) to stop the error. If that fails, roll back the driver or use registry tweaks to ignore MCCS.
Why Does This Happen?
This error code 0xC02625DA pops up when your monitor doesn't follow the MCCS (Monitor Control Command Set) spec. That spec controls things like brightness, contrast, and color settings over DDC/CI. When Windows or your graphics driver tries to talk to the monitor using MCCS commands, and the monitor responds with nonsense or doesn't respond at all, you get this violation.
I've seen this a bunch with cheap monitors or older ones that don't fully implement MCCS. Last month, a client had a Samsung SyncMaster from 2012 and he couldn't adjust brightness after a Windows update. The error kept appearing in Event Viewer. The fix was turning off DDC/CI in the monitor menu—took two minutes.
Sometimes it's not the monitor's fault. A buggy graphics driver can send wrong commands. Or a USB-C dock messes with the DDC channel.
Fix Steps (Main Solution)
- Disable DDC/CI on your monitor. Press the physical buttons on your monitor to open the on-screen display (OSD). Look for a menu called "System," "Others," or "PIP/PBP." Find DDC/CI and set it to Off. Every brand calls it different—LG calls it "DDC/CI," Dell uses "DDC/CI" too. If you can't find it, check the manual.
- Restart your PC. After disabling DDC/CI, reboot. The error should stop appearing.
- If you don't have DDC/CI option, update your graphics driver. Go to NVIDIA's or AMD's site and download the latest driver for your GPU. Use the auto-detect tool if you're not sure. For Intel, use Intel's assistant.
- After updating, restart again. Then check if the error is gone.
Alternative Fixes If That Doesn't Work
Roll Back the Driver
If you updated your driver recently and the error started, roll back. In Device Manager, expand "Display adapters," right-click your GPU, go to Properties > Driver tab > Roll Back Driver. If that button is grayed out, you need to uninstall the driver and install an older one from the manufacturer's site.
Registry Hack to Ignore the Violation
Warning: This is more involved. You're telling Windows to not check the MCCS spec. Open Regedit and go to:
HKLM\SYSTEM\CurrentControlSet\Control\GraphicsDriversCreate a new DWORD (32-bit) called MonitorMCCSIgnore and set its value to 1. Restart. This isn't officially supported but I've used it on a few systems where the monitor simply wouldn't cooperate.
Check for Firmware Updates for Your Monitor
Some monitors from Dell, LG, and Samsung get firmware updates that fix MCCS issues. Go to the manufacturer's support page, find your model, and download the firmware. Then follow their instructions to flash it. Usually it's a USB stick and a menu option.
Try a Different Cable or Port
Sometimes the DDC/CI signal gets corrupted over a long HDMI cable or a bad DisplayPort adapter. Try a different cable, ideally a shorter one. And switch from HDMI to DisplayPort or vice versa—that's solved a couple of stubborn cases for me.
Prevention Tips
- Keep your graphics driver updated, but don't jump on day-one releases. Wait a week to see if others report issues.
- If you don't use auto-brightness or external control software, keep DDC/CI off. It's only needed if you're using tools like DisplayFusion or Windows' built-in brightness slider on external monitors.
- When buying a new monitor, check reviews for MCCS compliance. Some cheap 4K monitors from lesser-known brands have terrible implementation. Stick with name brands like Dell, LG, Asus, or BenQ.
- If you're using a docking station, plug the monitor directly into the PC to test. Docks can mangle DDC/CI signals.
I know this error looks scary with all those capitals, but it's usually a simple fix. I've fixed it on a dozen machines and only once had to send a monitor back—it was a no-name brand that didn't follow any spec.