Mart version validation failed. Details: Mart Server is not reachable, please check network and mart service health.

While attempting to connect erwin DM to my mart server I get the error, "Mart version validation failed. Details: Mart Server is not reachable, please check network and mart service health." and I am not able to connect.   

Solutions:

Internet Explorer:

On the machine where erwin DM is installed:

1. Open Internet Explorer.
2. Click on internet options.
3. Go to the security Tab.
4. Make the security level to low.
5. Click on sites.
6. Add http://machine-name:18170/MartAdmin/
or
http://ip address:18170/MartAdmin/

Is JRE set correctly?

On the mart server host machine, make sure the JRE is set correctly.  Go to a DOS prompt and type,

set JRE

For r9.8 64-bit OS erwin DM that should return:

JRE_HOME=C:\Program Files\erwin\Mart Server r9\Jre64

If using SSL, on the erwin DM machine when installing the certificate,
Pick Local Machine
Place the certificate into the store Trusted Root Certification Authorities

Please also see, https://support.erwin.com/hc/en-us/articles/360001135551-After-upgrade-when-launch-Mart-server-Admin-getting-error-Mart-DB-version-is-not-compatible-with-Mart-Server-