Hi guys,
I have solved the issue of Invalid JSON string while uploading scorm module in my server.
Situation was i was trying to upload a scorm module which bigger in size.
I had already successfully uploaded some modules. But only one file was giving error which was the bigger in size that is 39 mb.
I increased the size limit of max_upload_filesize and post_max_size to 2000mb which was 8 mb before. But didn't solve my problem.
So i checked about IIS settings on google and i found that IIS settings allows by default 30 mb so i modify the Max upload parameter on IIS server.
And It solved my problem. Hope this may help you if same issue occurs.
Thanks,
Nikhil