This can be due to the jvm.dll in the scheduler connect directory being missing and thus the JDK in the scheduler connect is not able to not function correctly.
To check if this is the cause:
Run the java -version command from the Schedule connect folder. If the following error returns, this is the cause:
Error: missing 'server' JVM at 'C:\Program Files (x86)\CA\PPM\CA PPM Schedule Connect\jre\bin\server\jvm.dll'.
Please install of use the JRE or JDK that contains these missing components
Release : 15.5.1
Component : CA PPM OPEN WORKBENCH (OWB)
This issue was found on OWB 15.5.1, and not reproducible in 15.8.
To workaround this issue: Replace the jre directory in the schedule connector’s program files directory with an OpenJDK version that contains the server sub-directory and jvm.dll.
See also: OWB: 'Cannot start or find the Java' Error - Master KB for a list of known issues.