Some development builds introduce FST writing regressions. Test with:
Use external tools like GCITool.exe or WiiBackupManager to decompress to ISO.
The "FST" (File System Table) refers to the internal file structure of the Wii's operating system (IOS) that Dolphin emulates. When Dolphin starts or switches games, it attempts to update these temporary files in its user directory; if it cannot write the file, the emulator may fail to launch or crash during gameplay. dolphin iosfs failed to write new fst
Dolphin may not have write access to its own configuration folder, which traditionally resided in the "Documents" folder but now often lives in "AppData".
If none of the above work, it's time for advanced troubleshooting. Some development builds introduce FST writing regressions
Troubleshooting Dolphin Emulator: Solving the "IOS_FS: Failed to write new FST" Error
Some older versions of Dolphin (pre-5.0) had unstable ISO rebuilding code. Certain development builds (beta or nightly) might also introduce temporary regressions in IOSFS handling. When Dolphin starts or switches games, it attempts
: Try changing the NAND path in Dolphin’s settings to a different, non-system folder. Folder Rename : Some users resolve the issue by renaming the Dolphin Emulator folder in Documents to just : This will reset your settings and save states. Wii Menu Cleanup
Add the Dolphin installation folder and the user data folder (usually Documents\Dolphin Emulator ) to the exclusion list.
Some GameCube ISOs are marked as by the operating system. Additionally, if the ISO was ripped from a disc with unreadable sectors, the FST section might be corrupt to begin with.