Resolved - Invalid stage transition. Transition to stage is not in the process active path

On Dynamics 365 instance, with Lead to Opportunity Sales Process, when clicking on “next stage” button, I was receiving the following error:
"Invalid stage transition. Transition to stage 9291c1cb-0000-0000-a7ce-1c5f91a30734 is not in the process active path"

This error occurs when the business process workflow or one of its stages are corrupted. Hence the transition path will not find your stage.



Resolution:

The resolution of this is to create a duplicate process workflow to have a backup copy of the original one. On the business process workflow, click 'Save As'. This will create a duplicate copy of the process.

Next, find the stage id of the conflicting stage. One way to find the stage id and match it with the stage id in the error log is through the javascript:

Xrm.Page.data.process.getActivePath().getAll()

The above function lists all the stages in the process.

Now all you need to do is go to the original business process workflow, deactivate it, delete this stage, add a new stage and add all the steps by referring the duplicate one. Save and Activate the process. You may delete the duplicate process workflow.