Why can't I reach the LabTutor server Admin pages?

If you are see the following page when trying to log into your LabTutor Server's Admin pages from Internet Explorer version 11 on your Windows 7, 8, or 10 machine, your server may have an outdated security certificate. This is common with older installations of LabTutor Server (prior to version 4.5.3).


Check with a different browser, Firefox will display the following message:

Secure Connection Failed

An error occurred during a connection to mattg-win8.modern.adi.co.nz. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. Error code: SSL_ERROR_WEAK_SERVER_EPHEMERAL_DH_KEY

  •     The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
  •     Please contact the website owners to inform them of this problem.

Chrome usually provides a warning but lets you click through to the Admin Pages.


These older certificates use SHA-1, an older cryptographic algorithm which is now deprecated. As such, browsers no longer allow webpages to display that use these certificates.


To rectify this you will need to generate a new certificate for your LabTutor Server as follows:


Generate a new certificate and replace the existing one on LabTutor server:

  • Locate and Launch the Generate Admin Pages Certificate utility (C:\Program Files (x86)\ADInstruments\LabTutor Server\supportfiles)
  • Click Generate Certificate
  • Restart your LabTutor Server machine