Please describe the detailed steps to reproduce.

• Create a WORKFLOW project A
• Create a FREESTYLE project B
• In the freestyle project B, Add a build step of "Trigger/call builds on other projects"
• Projects to build: A

will get an error that states "A is not buildable"

Also, there is no post build in WORKFLOW project. I'm not quite sure if this is the same bug

Reproduction steps (tested with Jenkins 1.580.1):

1. Install Workflow plugin components
   • There are many components and I'm not sure what to install. At least, I could reproduce the problem with "Workflow: Job", "Workflow: Basic Steps" and "Workflow: Groovy CPS Execution" (and its dependencies)
   • The version of workflow-plugin is 1.1.
2. Install parameterized-trigger plugin.
3. Create a Workflow project "downstream"
   • Definition: Groovy CPS DSL
     • Script

       node {
           echo "hello world"
       }
       

     • Use Groovy Sandbox
   • This project works perfect by clicking "Build now".
4. Create a Freestyle Project "upstream"
   • "Trigger parameterized build on other projects" in Post-build steps.
     • Projects to build: downstream

Result

• An error message "downstream is not buildable" appears (atttached).
• upstream doesn't trigger downstream. no error messages are logged. The configuration looks completely ignored.

hierarchy:

Job
 - WorkflowJob
 - AbstractProject

parameterized-trigger plugin expects downstream projects AbstractProject as Job doesn't provide scheduleBuild2.

This is really what Jesse points in JENKINS-26050.