The update file can be downloaded from official Sony support pages or reputable archives. Depending on the console model and method, the file may need to be renamed: Often requires the filename PSP2UPDAT.PUP .
To use a custom firmware like , you often need to downgrade from a newer version (like 3.73) . psp2updatpup new download
Move your renamed PSP2UPDAT.PUP into that folder. The update file can be downloaded from official