Bottles 66.11 lands two days after 66.10, patching Flatpak regressions for UMU and MangoHud
Linux gamers finally got their hotfix this morning when Bottles shipped version 66.11. The release doesn't add features. It just resolves two Flatpak sandbox regressions introduced in 66.10 that broke UMU Proton launches and stopped custom MangoHud configuration files from loading.
Not exactly a feature dump. Just maintenance. But the timeline says a lot about the project's current pace. Creator Mirko Brombin released 66.9 on August 26, followed by the major 66.10 update on August 29, and then 66.11 this morning. Three versions in five days. The sprint makes sense once you look at what 66.10 actually changed. That build migrated to Flatpak manifest v3, bundled the UMU launcher directly into the cpak images, and added lazy loading for runner entries. Big architectural moves that inevitably tripped over themselves enough to warrant a same-week patch.
What actually changed
Pull request #4754 tightens the container build pipeline. Bottles was pinning its container image reference across every branch, which meant development and test builds were pulling stale or incorrect bases. The fix restricts that pinning logic to the main branch only, keeping reproducible builds intact while letting CI workflows pull fresh images on demand. Keep in mind that the cpak distribution channel is still newer than the official Flatpak build, so getting the container image pinning right matters more for reproducibility than it would for a traditional tarball release.
The second pull request, merged on release day, closed the two actual user-facing bugs. Issue #4759, reported by @pokegamer5547, caused games to crash with a FileNotFoundError: PROTONPATH ... is not valid, toolmanifest.vdf not found error whenever dedicated sandbox mode was enabled. Flatpak's strict isolation works great for security, but it has a habit of blocking tools that expect to find their own runtime files right where they were compiled. Bottles resolved it by exposing the UMU runner binary to the sandbox, which is honestly about as clean a workaround as you can get without rewriting the launcher itself.
MangoHud's issue was simpler. Custom .cfg files placed in ~/.config/MangoHud/ were being silently ignored because the XDG config path wasn't being preserved inside the Flatpak sandbox. Commit 7247c12 fixed that by mapping the config directory correctly, so your FPS overlay finally reads your preferences instead of defaulting to stock settings.
It's a tight release that reflects a team aware of its own CI failures. The underlying Flatpak manifest migration is the right call for long-term build stability, even if the sandbox layer keeps introducing friction for compatibility tools. The team caught both regressions within 48 hours, which speaks to solid testing pipelines on their end. Users running the Flatpak version should see 66.11 roll out through their package manager shortly, or you can grab it directly from Flathub if you prefer manual updates.
Head here for the change log.
