Support for Nintendo Switch 23.0.0
Atmosphère 1.12.0, released on September 27, 2026, adds support for Nintendo Switch system software 23.0.0. The release notes say the console should boot and Atmosphère should be fully functional with the update, while noting that the new system software changes how much memory is available to custom system modules.
Anyone upgrading to this release must also update fusee. The older fusee-primary component no longer exists and will not work with Atmosphère 1.12.0. The release package includes fusee.bin for the updated boot process.
More memory for custom system modules
Nintendo’s system software changes reduced the amount of memory Atmosphère could reclaim from the applet pool to less than 7 MB. Without another adjustment, launching browser applets such as the eShop could cause a crash. Atmosphère 1.12.0 addresses this with patches for the systemWeb, openWeb and LibAppletOff browser applets.
The patches remove allocations that the applets mark as reserved but do not access, allowing Atmosphère to reclaim about 9 MB. This experimentally raises the memory available to custom system modules to 16 MB. The project reports that preliminary testing found no apparent problems for the operating system or browser applets, but asks users to report issues because edge cases may still exist. The patches could also be replaced or removed in a future release if a better solution becomes available.
Kernel and system component updates
Several internal components were brought into line with the behavior of Nintendo Switch system software 23.0.0. Exosphère now reflects the latest secure-monitor behavior, including a new ConfigItem—the first such addition since system software 5.0.0.
Mesosphère, Atmosphère’s customized kernel layer, now supports a 42-bit address space and the new ShadowStack memory region. Its kernel random-number generation was also changed to CTR-DRBG. These are low-level compatibility changes that help the custom firmware track the platform behavior required by the newer system software.
The boot component now implements a change to battery I2C shutdown behavior that first appeared in system software 18.0.0. The project says this may be related to a battery-drain issue reported by users around that update, although further testing is needed before a connection can be confirmed.
Loader, erpt and pgl were updated to reflect current official behavior. The ro component now supports LZ4 frame-compressed NRO files, adding support for that compression format.
ZBIC support and bundled homebrew tools
ZBIC compression and decompression have been properly implemented in this release. Applications that use ZBIC should now launch and operate correctly, removing a compatibility problem for software that depends on that format.
The Atmosphère package includes hbl 2.4.5 and hbmenu 3.6.1. These bundled component updates accompany the 1.12.0 release.
What Atmosphère provides
Atmosphère is a work-in-progress custom firmware project for the Nintendo Switch. It is made up of several layers rather than a single replacement program. Fusée loads and validates later boot stages, Exosphère provides a customized secure-monitor environment, and Mesosphère supplies the customized kernel layer referenced in the release notes.
Other parts of the project provide virtualized or redirected NAND support, custom system modules, loader modifications and application-level Horizon OS patches. These components modify different parts of the Switch software stack and support the project’s custom firmware features.
The project is licensed primarily under GPLv2, with specific exemptions described in its documentation. Atmosphère credits the Switchbrew team and other contributors for research, documentation, development work and supporting projects.
Additional project maintenance
A Dockerfile has been added to the project, giving contributors a container-based option for the development environment. The release also completes the adoption of the R_DISCARD macro throughout the codebase where applicable, finishing work that began in version 1.10.0 and removing nodiscard warnings during compilation.
The release notes also cite general system stability improvements, without identifying individual user-facing fixes beyond the compatibility, memory, compression and component changes listed above.
