shouldn't do, but the reason it failed might.
you only get the UV Error when you've welded vertex which need to be seperate, make sure you weld ONLY the vertex that connect on the UV Map don't do a Weld all - it might look better on the model, but you can't export the skin otherwise.
it could even contribute to the failer to load as DBP might be looking specifically for all the UV Map vertex but they're not there so it failed to load it. (perhaps)
try this... first export the model to md3 - then reload it and export again this time as an MD3

you'll find it should export find - if you export the same model inside and out of the same scene so you can retain any skeleton information. There maybe a button or something somewhere (knowing max there will be but buried) to break all UV Vertex