how to fix several errors

I received the following errors when I try to save a project.
CExDLL:SaveToFile saveFile failed.
CMosaicMap:SAveTile save Tile failed.
CMosaicMap save Mosaic failed.
How do I fix them?
CExDLL:SaveToFile saveFile failed.
CMosaicMap:SAveTile save Tile failed.
CMosaicMap save Mosaic failed.
How do I fix them?