Quick answer: Your display chain — GPU, cable, adapter, or monitor — is refusing to assert the CGMS-A copy-protection signal, so Windows aborts playback of protected video. Swap the cable or adapter, update the GPU driver, or bypass the intermediate device.
What's actually happening here is that a media app (Netflix in Edge, a Blu-ray player, Windows Media Center back in the day, or some DRM-locked training video) asked Windows to negotiate Output Protection Management on the active display. OPM is the Windows API that lets a playback app ask the GPU "is the whole path from framebuffer to panel HDCP/CGMS-A compliant?" If the answer comes back negative, the app refuses to render the frame and surfaces 0xC0262515. CGMS-A specifically is the older analog-side copy flag that rides in the vertical blanking interval of component, S-Video, and composite signals. It also gets simulated over HDMI and DisplayPort in some driver stacks. The error means the driver reported that the endpoint can't carry that flag. Nine times out of ten it's a passive DisplayPort-to-HDMI adapter, a cheap USB-C dock, or an ancient driver from the OEM's support page that predates the monitor you're now using.
I've hit this on a Dell U2720Q hooked through a Cable Matters DP-to-HDMI dongle, and again on a Surface Dock driving an older 1080p panel. Both times the fix was removing a hop, not reinstalling Windows.
Numbered fix steps
- Strip the daisy chain. Unplug every adapter, splitter, KVM, capture card, and dock. Run one native cable straight from the GPU output to the monitor input of the matching type. HDMI to HDMI, DisplayPort to DisplayPort. If the error clears, you found your culprit — reintroduce each hop until it breaks again.
- Try the other output type. Some GPUs only assert CGMS-A on HDMI and not on DisplayPort (or vice versa) depending on what the monitor advertises in its EDID. If HDMI fails, plug into DisplayPort. If DP fails, try HDMI. This costs you nothing and rules out a driver path problem in about 30 seconds.
- Update the GPU driver from the chip vendor, not the OEM. Intel's or AMD's or NVIDIA's own site, not the Dell/HP/Lenovo support page. OEM drivers are frozen at ship time. The version you want is whatever's current this month. For Intel iGPUs, grab the Intel Driver & Support Assistant. For AMD, the Adrenalin package. For NVIDIA, the Game Ready or Studio driver — either works here.
- Force a mode change to reset OPM. Disconnect the display, wait ten seconds, reconnect. Or press
Win + Pand cycle to Duplicate then back to Extend. OPM sessions get stuck; tearing down the display topology clears the cached capability report. - Check for HDCP in the driver's control panel. NVIDIA Control Panel → Display → View HDCP status. AMD Software → Display. If it says "not supported" while you're on a compliant chain, the driver has latched a bad EDID. Unplug, power cycle the monitor (not just the PC), plug back in.
- Disable HDR and set 8-bit color temporarily. Some drivers drop the CGMS-A assertion when running 10-bit or 12-bit color on a link that's already near bandwidth limits over a marginal cable. Settings → System → Display → Advanced display → choose 8-bit and SDR. If playback starts, your cable is the bottleneck.
If that doesn't work
Swap the cable for a certified one. Not "high speed" marketing garbage — look for an HDMI Premium or Ultra High Speed cert, or a VESA-certified DP 1.4 cable. Passive DP-to-HDMI adapters are the single most common cause of this error. Active adapters (the ones with a chip inside, usually $25+) work because they re-clock and re-assert the protection flags. Cheap $8 dongles don't.
Test with a different monitor if you have one. If a known-good panel works, the original monitor's EDID is missing or corrupting the CGMS-A capability block. Some older Korean 1440p panels and a handful of Acer/Hannspree models shipped without proper HDCP keys — there's no software fix, the panel has to go.
If you're running this inside a VM (Hyper-V, VirtualBox, VMware Workstation), stop. Protected playback won't work through a virtual display at all. The hypervisor doesn't pass through the OPM handshake. You need a physical GPU passthrough or you need to play on the host.
Last resort: roll back the driver if the error started right after an update. Device Manager → Display adapters → right-click → Properties → Driver tab → Roll Back Driver. Then pause driver updates via Group Policy or the wuau.adm exclusion list, because Windows Update will happily reinstall the broken one within 48 hours.
Prevention
Buy active adapters when you need to convert signal types, and buy cables rated for the resolution and refresh you actually run. A 4K60 signal needs 18 Gbps of headroom; a random Amazon Basics HDMI 1.4 cable won't do it, and when the link trains down, the driver quietly drops CGMS-A support. Stick to one monitor per output unless you've confirmed MST works cleanly on that GPU. And when a driver update breaks protected playback, roll it back immediately instead of waiting for the vendor to patch it three months later — they rarely do, because almost nobody reports this error.