The " 7.0 Upgrade Assistant" was complaining about the .tasks index which was created in an older version 5.4 or around there. I assumed it was one of those system indexes that, if deleted, would be automatically recreated ES needed it. I've gone ahead and deleted the .tasks index and everything seems to work ok.
Was my assumption correct? Will the .tasks index be recreated if it's ever required?
ES version 6.6.1
yes, your assumptions are correct. The .tasks index currently only stores historical information about some of the past tasks that have run (reindex tasks, deleting ML jobs, and a few others), so you can safely delete it. It will be recreated when the next task will be indexed.
© 2020. All Rights Reserved - Elasticsearch
Apache, Apache Lucene, Apache Hadoop, Hadoop, HDFS and the yellow elephant logo are trademarks of the Apache Software Foundation in the United States and/or other countries.