I was trying to go through one of the Elastic tutorials, https://www.elastic.co/blog/aftershock-therapy-with-elasticsearch-and-csv-data-import (Aftershock Therapy with Elasticsearch and CSV Data Import), and Kibana kept crashing on me. By crashing I mean the webpage went blank except for displaying the "oops something went wrong" message in Chrome. This occurred after I went through the Machine Learning --> Data Visualizer --> Import steps. After some troubleshooting I realized that my CSV had about 90,000 rows in one column with commas that shouldnt have been there and just randomly started on the csv about 1/4 of the way down. Strange for sure. After removal of the commas the Import function worked as intended. I was unable to find anything in the Kibana or ES logs but with a little guidance, I may be able to sift through them a little better if theres something specific that I should be looking for. As I went through them nothing stood out but its possible that I just looked right past it.
So the solution is here, at least in this case, to check the csv data that your importing.