I have recently upgraded my elasticsearch cluster from version 6.8 to 7.1. Initially it seemed like the upgrade went well. Data continued to be indexed into elasticsearch and was available on kibana for the remainder of the day. However, the next morning the data suddenly stopped being indexed and hasn't appeared since. If I adjust the time period to the day of the upgrade and before, I can see data in discover. But nothing is appearing since then.
What puzzles me is that data continued to be indexed for 12 - 14 hours after the upgrade, but then suddenly ceased the next day.
I am fairly new to Elasticsearch and was looking to come here for some advise to see if I can find out the issue.
Hope you can help,