Latest stable (0.7.2) or latest dev (0.8-[...])? Can you upload your config.ini?

The 0.7.2 one.
How do I upload that?

Use vitashell and ftp to grab it from ux0:/data/mGBA/config.ini. It should be small enough that you can paste it in here.

It says 'we dont support that file type'

This is what i got from opening it though:

[gui.input.PSP2]
keyTake screenshot=-1
keyIncrease solar brightness=-1
keyDown=6
keyLeft=7
keyUp=4
keyDecrease solar brightness=-1
keyBack=13
keyCancel=12
keyRight=5
keyFast forward (held)=-1
keyScreen mode=13
keySelect=14
keyFast forward (toggle)=-1

[ports.psvita]
autoload=1
useBios=1
screenMode=2
autosave=1
sgb.borders=1
lastDirectory=ux0:/ROM/GBA/
frameskip=1
camera=1
gba.bios=ux0:/ROM/GBA/gba_bios.bin
fpsCounter=0

[gba.input.PSP2]
keyR=9
keyL=8
axisUpAxis=-0
keyStart=3
keyLeft=7
keyDown=6
axisLeftAxis=-1
keyB=15
keyUp=4
axisUpValue=64
axisDownAxis=+0
axisRightValue=192
axisRightAxis=+1
axisDownValue=192
keyA=14
keyRight=5
axisLeftValue=64
keySelect=0

Thanks.

Are you getting the crash when loading a game or the emulator itself?

Loading the emulator itself.
It loads up.
Shows no games. Then the error message.

Are you running in safe mode or unsafe mode? (Vitashell should tell you which mode is active if you're not sure)

Unsafe mode.
I didn't have this problem until after I updated MGBA.
I also tried that Kai GBA emulator in Adrenaline after this, and got a GPU crash.
Playing GBA games in Retroarch is still ok though.

Ok, one last question: does the folder ux0:/ROM/GBA/ exist?

No.
I have roms in a folder called "AAAROM" so that its quicker to find.

Perfect. That should be enough information for me to diagnose and fix this. In the meantime, delete the lastDirectory and gba.bios lines (you can do this directly in vitashell so you don't have to reupload it) and that should hopefully work around the crash.

Are those in the config in Tai?

No, they're in the ux0:/mGBA/config.ini file.

Thanks.
Ill try that

It actually worked.

Should be fixed in the dev builds now, for real. Will also be fixed in 0.7.3, when that comes out.