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In an unexpected twist, Mozilla had to rush out a hotfix for its latest Firefox release—version 139—after it caused major graphical glitches for users with NVIDIA graphics cards. Just a day after the update was rolled out on May 27, complaints began pouring in from users experiencing flickering videos and visual distortions while browsing, particularly on multi-monitor setups with mixed refresh rates. Mozilla swiftly identified the root cause and has now released version 139.0.1 to patch the issue.
Why Firefox 139.0.1 Was Released
Firefox 139 introduced several new features, including the much-awaited Full-Page Translations. But it didn’t take long for users on Reddit and Bugzilla to raise alarms about graphical artifacts affecting video playback and website rendering—especially on platforms like Instagram. The issue primarily affected Windows 10 users running NVIDIA GPUs across monitors with different refresh rates.
The underlying issue was Mozilla’s decision to re-enable a specific DirectComposition path behavior. In previous versions, a blocklist prevented Firefox from using DirectComposition on setups known to cause problems. However, Firefox 139 removed this blocklist, unintentionally reintroducing a conflict between Firefox’s rendering process and a longstanding NVIDIA driver bug.
This resulted in “video buffer leaks,” where content from one window would visually spill over into another, especially when switching between monitors running at 60Hz and higher refresh rates. Curiously, this did not affect 30 FPS videos, single-monitor systems, or setups using AMD or Intel graphics cards.
Mozilla acted fast. In just 24 hours, they released Firefox 139.0.1, which reverts the change by restoring the blocklist. Users can now safely install this version by navigating to Firefox Settings and checking for updates.
What Undercode Say:
The quick response from Mozilla highlights both the power and the risk of agile development in software engineering. On one hand, pushing new features like Full-Page Translation reflects Mozilla’s commitment to innovation. On the other, removing safety checks—like the blocklist—without robust cross-hardware testing can backfire, especially in a fragmented Windows ecosystem with diverse GPU and monitor configurations.
This incident also brings to light a more complex challenge: the fine line between using cutting-edge APIs like Windows DirectComposition and maintaining compatibility. Mozilla’s unique use of DirectComposition with “Surfaces rather than Swapchains” seems to be the differentiator that triggered this issue on NVIDIA systems. While this approach may offer performance advantages, it requires extensive validation, particularly on devices with mixed-refresh setups, which are increasingly common in gaming and creative environments.
From an architectural standpoint, the mention of a new rendering approach—”Layer Compositor”—set to be tested in Firefox Nightly is promising. This could bridge the gap between performance gains and stability by aligning Firefox’s behavior more closely with that of other browsers, possibly avoiding such pitfalls in future releases.
This event is also a clear reminder of the importance of telemetry and user feedback channels. Reddit and Bugzilla served as the early-warning systems that helped Mozilla pinpoint the issue. It’s a testament to the value of transparent community engagement and quick iteration cycles.
For end users, the key takeaway is to stay updated and to not ignore small glitches, as they might indicate larger systemic problems. And for developers, the lesson is clear: hardware compatibility must remain a top priority, especially when dealing with low-level graphical APIs and real-time rendering.
Firefox 139.0.1 now acts as both a fix and a cautionary tale in the fast-moving world of browser development.
Fact Checker Results:
✅ The issue was isolated to Windows 10 PCs with NVIDIA GPUs and mixed-refresh monitors
✅ Mozilla confirmed the bug originated from a removed blocklist affecting DirectComposition
✅ Hotfix 139.0.1 has restored the blocklist and resolved the graphical corruption 🎯
Prediction:
Expect Firefox to accelerate testing of the “Layer Compositor” in Nightly builds, aiming for broader hardware compatibility. Mozilla is likely to introduce more dynamic safety checks in future releases, allowing the browser to detect and adapt to problematic configurations in real-time. We may also see tighter collaboration between browser developers and GPU vendors to avoid similar conflicts going forward.
References:
Reported By: www.bleepingcomputer.com
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