Go to your control panel and check whether the Mendix 9.12.5 is installed properly or not. if it is installed properly . It will get listed in your program and feature section
Hello Venkat, did you find the root cause and solution for this ? I'm also facing the same issue, only for 9.12.5. It was working fine for last 2 months, all of sudden stopped working. Tried re-installing as well.