When you see “failed to write new fst,” it means Dolphin attempted to this map (usually when launching a title, saving emulated system memory, or installing a WAD file), but the operation could not complete due to a system-level permission or integrity failure.
If none of the above works, try these advanced steps:
Before jumping into solutions, identify which scenario matches your setup. The error usually falls into one of these six categories: dolphin ios-fs failed to write new fst
Real-time antivirus scanners (including Windows Defender, Malwarebytes, or McAfee) may flag Dolphin’s attempt to modify the FST.txt or NAND files as suspicious behavior, blocking write operations.
Here’s a piece of advice to help you diagnose and fix it: When you see “failed to write new fst,”
Did this error start appearing right after a or after you moved your Dolphin folders ?
Bad sectors, a full drive, or corruption on the physical hard drive (NTFS/FAT32 issues) can trigger this error, as the OS cannot commit the write to disk. Here’s a piece of advice to help you
Test the emulator. If fixed, you can re-enable Controlled Folder Access after adding Dolphin to the allowlist.