Issues exporting FBX file

Hi, I am having trouble when exporting an fbx for sketchfab - i have tried obj and the textures are horrible in sketchfab I am unsure why. So trying an fbx but am getting this error can anyone assist?

Hi CAPTURE2023,
what are your export settings? IS this also happening with 1 8k texture?

SO i am reprojecting the texture to a simplified model, which has given 3 x 8k textures. I am then attempting to export to sketchfab using the below settings

I have changed texturing settings to maximal texture count and reprojected with the same error appearing

If you try direct Sketchfab upload is it the same?

I get this error message

It seems like something is wrong with your project. Would it be possible to share it with us? If so, please contact our support.

ok what is the best way to do this?

https://www.capturingreality.com/technical-inquiry