Go to > Update & Security > Windows Security . Select Virus & threat protection > Manage settings .
"IOS_FS: Failed to write new FST" occurs when Dolphin cannot save system files to your storage, usually due to permission restrictions antivirus interference 🛠️ Key Fixes Disable "Controlled Folder Access" Windows Defender often blocks Dolphin from writing to your Windows Security Virus & threat protection Manage settings Manage Controlled folder access and turn it Run as Administrator Right-click your Dolphin executable and select Run as administrator to bypass standard file write restrictions. Check Folder Read-Only Status Right-click your Dolphin installation and Documents\Dolphin Emulator folders, select Properties , and ensure is unchecked. Manage Cloud Sync (OneDrive) If your Documents folder is syncing with dolphin iosfs failed to write new fst
: If permissions are strictly controlled, right-click the Dolphin executable and select Run as administrator to grant it full write access. Delete Corrupt DLLs : In some cases, a leftover or incompatible msvcp140.dll Go to > Update & Security > Windows Security
The error in Dolphin Emulator
The error in the Dolphin Emulator typically occurs when the application lacks the necessary permissions to modify its own configuration or virtual Wii memory (NAND) files . This often happens during startup or when installing WAD files . 1. Grant Administrative Permissions This often happens during startup or when installing
If you have tried all six fixes and the error persists, it may be a legitimate bug in a specific Dolphin version. Here’s how to report it: