Valve Updates Proton Experimental June 2026: Fixes for Call of Duty and More

Valve released a significant update for Proton Experimental on June 10, 2026, addressing technical inconsistencies for various titles, including the original Call of Duty and the upcoming Path of Exile 2. This update serves as a testing ground for future stable iterations of the compatibility layer, which is essential for running Windows-based games on Linux and SteamOS systems, including the Steam Deck. Our coverage here at In Game News tracks these frequent updates to ensure that PC players on Linux distributions remain informed about the latest stability improvements for their libraries.

Understanding the June 2026 Proton Experimental Patch

Proton Experimental functions as the primary staging environment for Valve’s development efforts before features are merged into the main, numbered Proton releases. As we reported, the June 10 update specifically targets rendering errors and input regressions that have hindered gameplay for users utilizing NVIDIA hardware or the Wayland display protocol. For those wondering what bug fixes are in the June 2026 Proton Experimental patch, the list is extensive and covers both legacy titles and modern releases.

Technical issues resolved in this release include:

• Call of Duty (2003): A fix was implemented to correct improper color rendering occurring within the main menu.
• Path of Exile & Path of Exile 2: Developers addressed a crash that occurred when specific characters were typed into the in-game chat interface.
• Exanima: The team fixed gamma display issues and addressed a performance regression that affected specific system configurations.
• Mirror’s Edge Catalyst: Addressed freezing issues on systems that do not utilize NVIDIA GeForce graphics cards, caused by the presence of nvapi.
• Vagante: Resolved a freezing bug that occurred at the character selection screen when using Wayland with NVIDIA hardware.
• No Limits 2 Roller Coaster Simulation: Fixed incorrect color rendering on systems using Wayland with NVIDIA GPUs.

Refining the Linux Gaming Experience

The update also addresses regressions introduced in earlier iterations of the Proton 11 development branch. For players who frequently switch between desktop and handheld modes, these fixes are essential for maintaining a seamless experience. For instance, Need for Speed Hot Pursuit Remastered now features functional input when the game is toggled to fullscreen mode on the Steam Deck. Furthermore, Guild Wars 2 users no longer need to contend with the KDE taskbar appearing over the game window while in fullscreen mode.

These adjustments highlight the iterative nature of the Proton project. By maintaining a dedicated testing branch, Valve allows the community to provide feedback on how to update Proton Experimental on SteamOS and identify issues before they reach the general user base. Users who have already installed the compatibility tool will see these changes reflected automatically in their Steam Downloads queue, as the client treats these as standard version updates.

Addressing Hardware-Specific Rendering Issues

The interaction between the Windows-based graphics APIs and Linux display protocols remains a focal point for the Proton team. The June 2026 patch highlights specific attention to the NVIDIA GeForce ecosystem. By resolving rendering errors in titles like No Limits 2 and freezing issues in Vagante, Valve is ensuring that users on diverse hardware configurations have a consistent experience. These fixes are particularly relevant for users who rely on Wayland, as the transition to this display protocol has historically introduced unique challenges for legacy and modern Windows software running through Proton.

Additional fixes included in the June 10 release cover:

• Psycho-Sleuth Demo: Corrected issues regarding video playback.
• Warhammer: Dark Omen (Classic): Resolved a bug where the map would display at an incorrectly low resolution on specific system setups.
• Moero Chronicle: Fixed a bug that caused the game to restart the intro video whenever the application lost focus.

For those interested in the broader ecosystem, our PC Gaming news coverage continues to monitor how these Proton updates influence the viability of Linux as a primary platform for high-end titles. While titles like Modern Warfare and other entries in the Call of Duty franchise have historically faced challenges regarding anti-cheat compatibility on non-Windows systems, the continued maintenance of the original 2003 title demonstrates Valve’s commitment to preserving older software through the Proton layer.

Frequently Asked Questions

What bug fixes are in the June 2026 Proton Experimental patch?

The June 2026 patch includes fixes for rendering issues in Call of Duty (2003) and No Limits 2, as well as stability improvements for Path of Exile, Path of Exile 2, Exanima, and Guild Wars 2.

How to update Proton Experimental on SteamOS?

Proton Experimental updates automatically through the Steam client; if you have it installed, the update will appear in your Steam Downloads queue.

Does Path of Exile 2 work on Linux with Proton Experimental?

Yes, the latest June 2026 patch resolves specific crashing issues in Path of Exile and Path of Exile 2 that were triggered by certain character inputs within the in-game chat.