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What does "The timestamp signature and/or certificate could not be verified or is malformed" mean?

If you tried to join a meeting and hit this error, it means Windows is unable to update its internal certificate. This can be caused by many scenarios, but is easily resolved.

  1. In the "Error - GoTo Opener" window, select Show log file.
  2. Search the log file for the latest instance of This file should end with G2MCoreInstExtractor.exe.
    Note: An example of the file is
  3. Copy the file link and paste it in a new browser.

    Result: This will download the new file to your computer.

  4. Once downloaded, open your Downloads folder, find and then right-click on the newly downloaded file.
  5. From Properties > General > Security, select Unblock > Apply.
  6. From Digital Signatures, select Details > View certificate to verify the "Valid from" dates have not expired.
  7. Update as needed and then select OK.
  8. Rejoin your meeting.