when do you get 414 error - before form submit when you navigate through the steps of form-wizard or at the time of form submit on last page of wizard?
If you get the error on last page at the time of submit in submission response then change the GET method to POST. If you get the error while navigating then you're appending too much information in the url and you should customize it to use cookie/sessionStorage or other mechanisms based on the framework/libraries you use.