This issue has two possible causes.
- The computer is not connected to the internet. Troubleshoot the internet connection and retry.
- Internet Explorer's security settings need to be adjusted.
- Open Internet Explorer.
- Click Tools > Internet Options.
- Click the Advanced tab.
- Scroll down until you reach the Security heading.
- Uncheck the box next to Check for server certificate revocation.
- Restart your computer, then try to upload again.