Help resolve error exporting JSON file from SPINE 2d

I have data files (JSON) of spine character which i imported in spine and changed original graphics to new but im unable to export the file to JSON. texture pack is working, just error while exporting to json. i need your help to solve the issue if you are skilled in spine2d software. thanks! following is the error log : Sorry, an unexpected error has occurred: [login to view URL] at Fj.a(SourceFile:220) at Fj.a(SourceFile:290) at com.esotericsoftware.spine.editor.Editor.b(SourceFile:831) at ai.a(SourceFile:270) at ai.b(SourceFile:235) at mR.b(SourceFile:103) at [login to view URL](SourceFile:191) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]$200([login to view URL]) at [login to view URL]$[login to view URL]([login to view URL]) at [login to view URL]$[login to view URL]([login to view URL]) at [login to view URL](Native Method) at [login to view URL]$[login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL]) at [login to view URL]([login to view URL])