Troubleshooting Dolphin: How to Fix "IOS_FS: Failed to Write New FST"
The error "IOS_FS: Failed to write new FST" in the Dolphin Emulator can be incredibly frustrating, often popping up repeatedly and preventing games from launching. This issue typically indicates that the emulator is being blocked from writing to its own system or user files. Here is how you can resolve this and get back to gaming. 1. Disable "Controlled Folder Access" (Windows)
The most common culprit is Windows Defender's "Controlled Folder Access" feature, which blocks apps from modifying files in protected directories like Documents. Open Windows Security > Virus & threat protection.
Click on Manage settings under "Virus & threat protection settings."
Scroll down to Controlled folder access and click Manage Controlled folder access.
Either toggle it Off entirely or click Allow an app through Controlled folder access to add Dolphin.exe to the whitelist. 2. Add an Antivirus Exclusion
Third-party antivirus programs (like Avast or Bitdefender) often flag Dolphin’s constant read/write actions as suspicious.
Open your antivirus settings and find the Exclusions or Exceptions list. dolphin ios-fs failed to write new fst
Add both the Dolphin installation folder and the Dolphin Emulator user folder (usually located in Documents or %AppData%) to the list. 3. Relocate the User Folder
If file permissions in your Documents folder are corrupted or locked by a cloud service like OneDrive, moving the user directory can fix the problem. Open Dolphin and go to File > Open User Folder. Close Dolphin.
Move the entire Dolphin Emulator folder to a different location (e.g., directly onto your C:\ drive or another internal disk).
To tell Dolphin where the new folder is, you can create a blank file named portable.txt in the same directory as your Dolphin.exe. This forces Dolphin to use its local folder for all settings and saves. 4. Check for Disk Errors
Occasionally, this error is caused by minor file system corruption on your drive.
Right-click your SSD/HDD in File Explorer and select Properties. Go to the Tools tab and click Check under "Error checking."
Follow the prompts to Scan and repair drive if any issues are found. Summary Checklist Whitelist Dolphin.exe in Windows Security. Troubleshooting Dolphin: How to Fix "IOS_FS: Failed to
Disable real-time protection temporarily to see if the error persists.
Check OneDrive to ensure it isn't "syncing" and locking your Documents folder.
Run as Admin (only as a last resort, as this can sometimes cause other permission issues).
Which version of Dolphin are you currently using, and are you on Windows or Android? How to Fix Dolphin issue: IOS_FS: Failed to write new FST
hey guys what's up and welcome back today in this video I'm going to show you how to fix this issue while opening dome in your PC. YouTube·TeckBeen Gaming Tips Error when starting Dolphin emulator in Launchbox: "IOS_FS
No. Saves are stored separately (usually in Dolphin/Load/User/Wii/title/). However, the error can prevent saves from being written until resolved.
Before jumping into fixes, identify the most likely culprit. There are four primary reasons for the "failed to write new fst" message. Q: Does this error delete my save files
A corrupted virtual Wii NAND can cause filesystem errors. In Dolphin iOS:
Wii folder inside Dolphin/Load/.In extremely rare cases, the error is caused by the game image itself. Some poorly constructed ROM hacks or fan-translations intentionally corrupt the FST to bypass anti-piracy, which backfires on Dolphin. If you have tried all nine fixes and the error persists:
View > Show Log)A failing hard drive or file system errors can cause this. Run a disk check:
chkdsk /f C: (Replace C: with your game drive letter).If the error occurs while installing WADs or updates:
Option A: Perform a NAND Refresh
Option B: Use a BootMii NAND Backup If you have a real Wii, you can dump a healthy NAND and load it into Dolphin via Tools > Manage NAND > Import BootMii NAND Backup.