Restore Stardew Valley's mod launcheron Steam Deck

If Stardew Valley opens on your Steam Deck but SMAPI never appears, check which version of the game Steam is launching before reinstalling your mods. Native Linux Stardew needs Linux SMAPI; a game running through Proton needs the Windows version. For a native installation, Steam launch options should be empty. If a game update has replaced the modded launcher, running the Linux SMAPI installer again is the documented repair.

Identify native Linux or Proton first

Select Stardew Valley in your Steam library, scroll to GAME INFO and look under Steam Deck Compatibility. The SMAPI player guide identifies Steam Linux Runtime as native mode and Proton followed by a version number as the Windows route. Write down what you see. These are different installations to troubleshoot, even though both start from a Steam Deck. This guide's repair steps are for the native Linux game.

If you deliberately chose Proton to work around a separate multiplayer problem, keep that distinction in mind before changing it. SMAPI's Deck instructions provide a separate manual Windows installation and warn that modded saves will not use cloud saving through that route. A working native mod loader does not prove an online-service problem is fixed. Back up your existing saves and Mods folder before changing installation type, and retain your previous settings so you can restore them.

Remove a Windows launch override

For native Stardew, open the game's Properties, then General, and clear the Launch Options box. Save a copy of anything already there first. The SMAPI troubleshooting guide explicitly says Linux launch options should be empty. A Windows path ending in StardewModdingAPI.exe with %command% belongs to the Windows setup; pasting it into a native Deck installation does not configure the Linux launcher.

PC Gamer's February 2026 mod-installation guide shows that Windows Steam command in its general Steam-user steps. On Steam Deck, use the platform-specific SMAPI instructions instead. If Steam is forcing Proton and you intend to return to native mode, Properties > Compatibility contains the "Force the use of a specific Steam Play compatibility tool" control. Remove the forced Proton selection, allow Steam to finish any required download, and check GAME INFO again before installing Linux SMAPI.

Repair the native launcher with the installer

In Desktop Mode, download the current SMAPI installer from SMAPI.io and extract the ZIP somewhere outside Stardew's game folder. At this check, the site offers SMAPI 4.5.2 and requires Stardew Valley 1.6.14 or later. Version 4.5.1 fixed a Linux/macOS installation error in 4.5.0, so do not keep retrying an old installer when a supported update is available.

1. In the extracted installer directory, make sure install on Linux.sh and internal/linux/SMAPI.Installer are executable. The Linux guide permits doing this through your file explorer.
2. Run install on Linux.sh and follow its prompts. If it asks for the game location, open Stardew Valley's Properties in Steam and use its option to browse the installed files. Select the actual installation, including one on removable storage.
3. Choose installation, then launch the regular Stardew Valley entry through Steam. The Deck guide specifically recommends rerunning the installer when the SMAPI window disappears after a game update.

Do not merely copy the extracted installer files into the game directory. Use the installation process rather than guessing which executable to rename. Success at this stage means SMAPI starts alongside the game. That confirms the loader is running; it does not establish that every downloaded mod is compatible or installed correctly.

Read the error before changing more files

If the game still will not launch, open a terminal in the actual game folder and run ./StardewModdingAPI. The Deck guide gives a specific diagnosis for an error saying the required libhostpolicy.so library was not found: Linux SMAPI has been paired with the Proton version of Stardew. Return to the version check and match the installer to the game; do not download an arbitrary replacement library.

If SMAPI starts but a mod fails, use its log rather than repeating the launcher repair. SMAPI.io's Linux log instructions point to ~/.config/StardewValley/ErrorLogs. Use SMAPI-crash.txt if present, otherwise SMAPI-latest.txt, in the site's log parser. It shows game and SMAPI versions, the game folder and individual mod errors. Update the named incompatible mod or required dependency according to its author's instructions; a loaded SMAPI window alone is not the success check.

Keep a route back to the unmodded game

To distinguish a mod-loader problem from a base-game problem, the SMAPI troubleshooting guide says Linux players can launch StardewValley-original from the game folder. Check whether the unmodded game reaches its title screen before loading a farm that depends on mods. If you decide to remove SMAPI, rerun its installer and choose uninstall. For native Steam, keep launch options empty. Preserve your backed-up saves and mod folders while investigating any remaining base-game error.