@abj OK great, thanks for the reply! That was what I suspected but helpful to have confirmation.

@sleve_mcdichael This is exactly what I was looking for. I installed Retropie and about 100 NES, SNES ROMS, themes etc. on a 256 card but looking to do USB rom service on NESPI 4 case on a 256 SSD. Thought I would be able to make an image and then install it on a 128 card but no, Win32diskimager says the card is too small. I thought there is no freaking way this card was too small but now I know it copied the unused sectors too.
Thanks for tip about PiShrink! You hopefully saved me $40 on another SD card! Thanks again!

You can transfer BIOS and ROM files - like usual - but the emulator configs usually contain platform specific settings which should not be transferred. It's ok to transfer EmulationStation's setting - gamelists and metadata.

@sleve_mcdichael sorry yeah that's what I meant to ask but didn't word it properly lol I'll try this today and see how it goes, and I've no problem shaving a few GB off if it means saving my build lol

@chaoseffect I think I got it, Win32DiskImager says something about formatting the E: drive after it writes, this time I selected nothing and put the SD card in the Pi4. Everything boots up as expected. I will use this new SDcard for a while to make sure everything is good.

@pjft said in Problem with backup using Windows:

@retrus You may use rpi-clone to clone your card to another, smaller one, and then run the backup on Windows.

https://github.com/billw2/rpi-clone

Thanks for advice. I bought 2TB ssd :)

@erbright said in Unable To Backup RetroPie Image:

Win32DiskImager - Doesn’t work. I create the image and try to mount it to make sure it works and Windows tells me it's corrupted. This happens over and over again.

This is all you needed to do, it did work, you just can't mount it under Windows.