According to Jenkins documentation, post should be usable after all steps or a single step

 

The post section defines one or more additional steps that are run upon the completion of a Pipeline's or stage's run (depending on the location of the post section within the Pipeline).

 

From <https://jenkins.io/doc/book/pipeline/syntax/#post>

 

I am encountering this error

 

WorkflowScript: 17: Expected a stage @ line 21, column 3.
                   post
     ^

1 error

 

for the following:

 

pipeline
{
    agent any

    stages
    {
        stage('Some Action')
        {
           steps
           {
             script
             

{                println "do something"              }

           }
        }
        post
        {

             always

           

{                 println "Do some work"             }

        }
   }
}

 

I believe this syntax correct. I can find no examples to show otherwise. Hopefully you do not mean stages' run.