PSP Firmware 5.50: ISO/CSO Files Not Showing Up – Fixes

A common headache on 5.50 (and 6.xx). Here’s a structured troubleshooting checklist.

Likely Causes

• Wrong file extension (must be .iso or .cso, not .rar/.zip).
• Corrupted download/transfer.
• Incorrect folder on Memory Stick.
• Game incompatible with 5.50 (needs 6.xx kernel).
• Failing Memory Stick or PSP hardware.

Step-by-Step Fixes

1. Verify files: Re-download from a trusted source; compare MD5/SHA-1 if available.
2. Correct placement:
   • .iso → ms0:/ISO/
   • .cso → ms0:/ISO/ (modern CFW reads both here) or ms0:/GAME/ (older CFW).
3. Format Memory Stick on PC (FAT32, 32 KB allocation) for a clean filesystem.
4. Clear PSP cache: Settings → System Settings → System Information → “Clear Cache” → reboot.
5. Update CFW: If on 5.50 GEN or M33, upgrade to 6.61 PRO-C2 / ME-2.3 / Infinity for best compatibility.
6. Test a known-good ISO (e.g., a small homebrew) to isolate the issue.
7. Inspect hardware: Try another Memory Stick; check UMD drive ribbon cable if games also fail.

Extra Tips

• Extract ISOs from archives before copying.
• Use reputable sources only.
• Check compatibility lists for your specific game + CFW version.

Still stuck? Post your CFW version, Memory Stick size, and the exact game on r/PSP or Wololo forums.