Export Error: Image Not Supported

I started getting this error when I textured one of my objects. I only have one texture image and it was exporting fine for a while.
See Latest export example

Blend file attached.

I started getting this error when I textured one of my objects. I only have one texture image and it was exporting fine for a while.

I can't see any errors when try to export your attached .blend file. But this type of error always occurs when you attache a texture on the World with not an Enviroment type of the texture.

Like this:

Thanks much. I must have done that by mistake. I reset my sky texture and now the error is gone.