This issue is caused by: Security settings or another application is blocking access to the Respondus servers that LockDown Browser uses at startup.
To solve this issue, please follow the below steps:
- Temporarily turn off all anti-virus and firewall software on the computer and try the exam again.
- Reset your computer's internet options.
- If the problem persists after steps 1 and 2 above, the problem could be caused by your computer, ISP, or network blocking access to the Respondus servers.
- If the problem persists after following the above steps, try using a different WiFi network.
- Finally, if a deadline for an exam is near, you may want to consider using LockDown Browser on another Windows or Mac computer.
For more details, please refer to this article.