Custom Application.master - workflow error

I have a custom application.master page to customise the look and feel of the _layout page. I accidentally copied the search control onto the application.master. All works well until you try to create a workflow and it would not work, and you will recieve an error(not very friendly error). Existing workflow can be used, you just can't create new workflows.

So if you have the same problem as I do, I hope this post saves you some time.