Invalid File Contents When Uploading to eLearning

What exactly do you want to upload? Is it a raw cptx project or is it published HTML output? In the second case make sure you published the project with the option 'zipped' activated in the publishing dialog box, and if you created a SCO, you will have to deactivate Reporting under Quiz Preferences. The server used in the community is not a LMS and this means you can only upload the output when Reporting is disabled.