Wangan Midnight (Export) Invalid ISO9660 Volume Descriptor about play-

[kim-sama]

That rom isn't dumped correctly. The game is originally a CD Rom, but CD Rom images can't be .iso. So in order to get it working, you need an actual CD Rom image which is .bin. Or find away to fix the rom and make it .bin

[jpd002]

I think the CD-ROM .iso could be an issue as pointed by @kim-sama, so, that can be something to investigate. Also, can you share with us the chdman command line you've used to convert the .iso file to .chd?

I think you could also try to specify the .iso file directly in the .arcadedef as I think it doesn't really matter which format is used as long as it's one of the supported image formats by the emulator.

[SK91no]

I think I used extractcd and convertcd on what I extracted after, tried both results and got that