Fixing "Corrupted Data" Errors for ISO/CSO on PSP Firmware 5.50+

Why It Happens

Firmware 5.50 introduced stricter file integrity checks. Older ISO/CSO rips—especially those with non-standard headers, bad sectors, or incorrect compression—fail these checks and show as "Corrupted Data."

Solutions (Try in Order)

1. Re-download & Verify Files

• Obtain ISOs/CSOs only from reputable preservation communities (e.g., Redump, No-Intro verified sets).
• Verify MD5/SHA-1 checksums match the database entry. Tools: HashTab (Windows), shasum (macOS/Linux).

2. Format Memory Stick Correctly

1. Insert Memory Stick into PC (via USB adapter or PSP in USB mode).
2. Format as FAT32 (not exFAT, NTFS). Allocation unit: 32KB or default.
3. Create folder ISO (uppercase) on the root directory.
4. Place verified ISO/CSO files directly inside ISO/.

3. Install Custom Firmware (CFW) – Best Compatibility

CFW (e.g., Pro CFW (6.61 PRO-C2), ME/LME) patches the system to run ISOs/CSOs natively without the strict OFW checks.

• Pros: Near-100% compatibility, plugins, homebrew, PS1/PSP/PSX support.
• Risks: Permanent (IPL) CFW can brick if installed incorrectly. Use temporary (FastRecovery) CFW for safety.
• Prerequisites: PSP 1000/2000/3000/Go on 6.60 or 6.61 OFW. Backup NAND first!

4. Convert ISO → CSO (or Vice Versa)

Use ISO Compressor (PC) or PSP ISO Compressor (homebrew) to re-compress. Some games run better as CSO (less seek time), others as ISO (less CPU overhead).

Community Resources

• Wololo.net – PSP/Vita hacking hub
• r/PSP – Active community, troubleshooting threads
• PSP Developer Wiki – Technical reference

Always backup your saves and Memory Stick before attempting CFW installation or formatting.