Error Visualize: Field data loading is forbidden on IIS_Method

I have added a new field called "IIS_HTTPVerb". It contains values such as GET, POST, DELETE and PUT.
I am trying to add a BAR visualization on this field. Based on these values I need to create multiple bars(X AXIS) and Y AXIS displays the count.

But i am getting this error "Visualize: Field data loading is forbidden on IIS_Method"" on hitting the EXECUTE button. What is wrong here ??

What version of Kibana and elasticsearch are you using? Are you using logstash?

Performing an aggregation on a field with disabled field data will give this error. Is this field analyzed? If there's a .raw field available, it's likely you want that instead.

https://github.com/elastic/elasticsearch/issues/15267 is a good resource for more discussions on this.

I am using the latest version of Kibana, ES and Logstash.

Can you let me know how can I enable a field for aggregation ? Is this something I can do in logstash ?