Upgrade notes (2.3 to 2.4)
To upgrade Optimize to version 2.4.0 please perform the following steps first: Migration & Upgrade Instructions.
Here you will find information about:
- known issues,
- changes in the supported environments,
- any unexpected behvavior of Optimize (e.g due to a new feature)
Changes in the supported environments
With this Optimize version also the supported versions of Elasticsearch changes. Now Optimize only connects to versions 6.2.0 and later. See the Supported Environments sections for the details. Hence, you need to upgrade Elasticsearch to use the new Optimize version. See the general Elasticsearch Upgrade Guide on how to do that. Usually, the only thing you need to do is to perform a rolling upgrade.
Confusing warning during the upgrade
On executing the upgrade you may see the following warning a couple of times in the upgrade log output, which you can safely ignore. The upgrade itself amends the relevant index settings so the warning will be resolved afterwards:
Deprecated big difference between max_gram and min_gram in NGram Tokenizer,expected difference must be less than or equal to: 
Misinterpreted cron expressions
The configuration of Optimize allows you to define when the history cleanup is triggered. For that, the Cron expression notation is used. However, the values are incorrectly interpreted in Optimize. For example, the
historyCleanup.cronTrigger configuration has the default value
0 1 * * *, which should be 1am every day. Unfortunately, a bug causes this to be interpreted as every hour.
To fix this just use the spring cron expression notation. For instance, the default value for
historyCleanup.cronTrigger would then be
0 0 1 * * *.