Convert your game to (uncompressed) or extract the FST :
Repeat the process to exclude your global user settings folder, which defaults to C:\Users\[YourUsername]\Documents\Dolphin Emulator\ . 2. Grant Administrator Privileges
In this article, we will break down exactly what this error means, why it occurs, and—most importantly—how to fix it step by step.
Have you encountered this error in a different context or found another solution not listed here? Share your experience in the Dolphin community forums to help fellow emulation enthusiasts. dolphin iosfs failed to write new fst
: Tools like Windows Defender , Avast , or Bitdefender often flag Dolphin’s constant read/write operations in the "Documents" folder as suspicious .
Implementation details (suggested diffs / places to change)
Go to Windows Security > Virus & threat protection > Manage settings . Under Controlled folder access , click Manage Controlled folder access and either turn it off or add Dolphin.exe to the allowed apps list. Convert your game to (uncompressed) or extract the
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Sometimes, the error is not due to your setup but is a bug in a specific Dolphin version. For example, users have reported the issue appearing or disappearing after updating to versions like 2506 and 5.0-16xx and later.
If you are a fan of GameCube or Wii emulation, you have likely used Dolphin Emulator to relive classics like The Legend of Zelda: The Wind Waker , Super Smash Bros. Melee , or Mario Kart: Double Dash!! . Dolphin is an incredibly powerful and sophisticated emulator, but with great power comes occasional complexity. Have you encountered this error in a different
The IOS_FS: Failed to rename temporary FST file error is typically a minor "handshake" issue between Dolphin and your operating system's security or file management software. For most people, the fix is simple: exclude Dolphin from your antivirus or cloud-sync folders.
If you are using Dolphin in Portable Mode, switching to the standard, non-portable configuration is the single most effective fix. The development team has noted that this configuration can cause unforeseen issues with file handling.
Either turn it or click Allow an app through Controlled folder access and add Dolphin.exe to the list. 2. Run as Administrator
The folder where Dolphin stores user data may be set to "Read-Only," preventing the emulator from updating configuration or save files.