The error may occur when uploading a presentation using Internet Explorer. Please try the following to solve the error:
- Open Internet Explorer
- Click on "Tools" or the cog icon(this is located on the top right corner of the browser)
- Select "Internet Options" from the list
- From the "General" Tab - "Browsing history" section click on "Settings"
- From the "Temporary Internet Files" tab make sure the option "Every Time I visit the webpage" is selected
- Click "Ok" and "Apply.