What is error 80020148?

I get an error when starting an ISO saying 'The game could not be started (80020148)' why am I getting this error?

Thanks for the help!

do u have cfw?

try putting a UMD game disc in your psp, i think thats whats wrong.

Thanks for the help it's greatly appreciated! To answer your questions:

I have custom firmware 3.90 M33 but I've had this error with CFW 3.40 OE & 3.52 M33.

Also I always have a umd game in the slot, so it's definitely not that.

According thos this guide: http://www.psp-hacks.com/forums/viewtopic.php?id=119276

80020148 - Unsupported PRX type | This error also seems to appear when you are running an iso with a fake mem.
-Upgrade to a newer custom firmware, or u are using official firmware and u need to downgrade then install CF.
-If not, it is probably a config error/bug and 99% of the time it will be fixed if u "delete flash1 and reset settings" in Recovery>Advanced.
-Often occurs when upgrading from a older OE/SE to M33.
-can also be bad/corrupt iso
-can be from not having 1.5 addon installed when running some homebrew(fat only)
-can be fake memcard.
-also occurs with older SE/OE firmware if u have umd mode set to M33 driver(fixed by changing to sonynp9660 or put in a umd)
-also can be fixed by upgrading to 3.52M33 from older CF.
but most of the time it is a upgrade bug in flash1.

I hope this helps.

[DarkPacMan77]

Jay-Jay listed some great solutions and to my knowledge they are all credible solutions as well. I do have one tiny thing to add though. There have been two times in my history of dealing with PSP errors that the 80020148 error has occured for DIFFERENT reasons than what Jay-Jay listed. Although minor, for some reason, I've helped people out before that had that error and it came down to changing their clock speed to 222mhz (stock) or 300mhz (just under 333mhz). I think that their problems were more related to individual UMD/ ISO usage, but I just thought I'd throw that piece of wisdom out there

-DarkPacMan77-

The reason it says that is that the iso is not meant for your firmware(never heard of it)or you didnt install it right

Oh ok, i took a wild guess, no one really knows for sure why they get that error, it is probably asked about 90% out of all the error codes.