Mozilla has swiftly addressed a critical display bug that plagued Firefox users with Nvidia graphics cards following the release of version 139.0 just three days prior. The emergency patch, Firefox 139.0.1, specifically targets visual artifacts and screen corruption issues that emerged in multi-monitor configurations with mixed refresh rates.
Affected Systems:
- Nvidia GPU users with multi-monitor setups
- Mixed refresh rate configurations (e.g., 144Hz + 60Hz monitors)
- Windows systems using DirectComposition
Unaffected Systems:
- Intel or AMD graphics users
- Single-monitor configurations
- Non-Windows operating systems
The Problem Emerges Quickly After Firefox 139.0 Launch
Firefox 139.0 launched on May 27th with several anticipated features including custom new tab backgrounds and full-page translation support for compatible extensions. However, the celebration was short-lived as user complaints flooded Reddit forums and community discussion boards within hours of the update's release. Users reported experiencing severe graphical anomalies, including strange lines, flickering, and visual corruption when browsing media-heavy websites like YouTube, Facebook, Instagram, and Reddit.
Multi-Monitor Setups Bear the Brunt of Display Issues
The bug predominantly affected users running multi-monitor configurations where displays operated at different refresh rates, such as a primary 144Hz monitor paired with a secondary 60Hz display. Users discovered that playing 60 FPS media content on the secondary monitor would trigger visual artifacts to appear on the primary high-refresh rate display during interaction. This created a frustrating browsing experience where simple navigation tasks became visually disruptive.
DirectComposition Blocklist Removal Triggers Graphics Driver Bug
Mozilla's investigation revealed that the company had removed a specific blocklist in Firefox 139.0 that previously prevented DirectComposition from being used with certain Nvidia GPU configurations. This blocklist had served as a protective measure for multi-monitor setups with mixed refresh rates. The removal inadvertently exposed an underlying graphics driver bug that manifested as the widespread display corruption issues users experienced.
Technical Differences in Firefox's Graphics Handling
A Mozilla developer explained that Firefox handles graphical buffers differently from other browsers, utilizing Surfaces instead of Swapchains with Windows DirectComposition technology. The company has been working on implementing a new Layer Compositor designed to more closely mimic how other browsers render elements on screen. This architectural shift may have contributed to the decision to remove the blocklist, though Mozilla has not definitively confirmed this connection.
Quick Workaround and Official Fix Available
Before the official patch release, technically savvy users discovered a temporary workaround by manually disabling the gfx.webrender.dcomp-video-hw-overlay-win flag in Firefox's configuration settings. However, Mozilla's official Firefox 139.0.1 update provides a permanent solution without requiring manual configuration changes. The patch is now available through Firefox's automatic update system, accessible via the Help menu's About Firefox section.
Firefox Version Timeline:
- Firefox 139.0: Released May 27th, 2025
- Firefox 139.0.1: Emergency patch released May 30th, 2025
- Bug report: Bugzilla 1968876
Manual Workaround:
- Toggle
gfx.webrender.dcomp-video-hw-overlay-winflag to false
Limited Impact Scope and Update Recommendation
The display artifact issue specifically affects users with Nvidia graphics cards in multi-monitor configurations with varying refresh rates. Single-monitor setups and systems using Intel or AMD graphics remain unaffected by this particular bug. Mozilla recommends that affected users update to Firefox 139.0.1 immediately to restore normal browsing functionality and prevent further display corruption issues.