Im not able tonew add workflow to an existing workflow

[Neha Pradhan]

So I added the the new workflow with the existing workflow and clicked on published 
now it says "The current status of each issue needs to be changed so that it is compatible with the new workflows"

Any ideas what is to be done for this ?

[Nic Brough -Adaptavist-]

Follow the prompts through.

You are changing the workflow and you have changed the possible status, removing at least one status. 

When you do this, Jira can't leave existing issues with status you have removed, it needs to give them a status in the new workflow so that they can be used.  So you need to tell it what new status to move issues to.