I have a Raspberry Pi B with version 3 beta 3, I can get most things working that I want, but GBA doesn’t work.
I just get “You have and incorrect BIOS image”, I have copied the gba_bios.bin into the /home/pi/RetroPie/BIOS and /opt/retropie/emulators/gpsp folders
its 16k and I have used it before.
I am not sure what to try next?
Try obtaining another bios from another source or try recopying it. Sometimes transferring files can partially transfer or corrupt a file (due to unstable connections or some similar sort). See if the problem persists.