Re: Invalid JSON String Internal Server Error

For anybody who still struggles with this, the solution is to increase the "Maximum allowed content length" Request Filtering value in IIS to a value larger than the size of your backup file (or scorm package or whatever type of file you're dealing with).

1. Open the IIS Manager.
2. Navigate to your site in the Connections manager pane.
3. Open the Request Filtering feature.
4. Click Edit Feature Settings.
5. Increase the value under Maximum allowed content length. The default is 30mb. Increase it to a value slightly bigger than the file you're working with.
6. Restart IIS.