@spartakus
You will want to review the release notes for all release between 1.23. and 1.28.1
https://cwiki.apache.org/confluence/display/NIFI/Release+Notes/#ReleaseNotes-Version1.23.0
You'll notice a number of components deprecated. Deprecated components are not removed, but that are marked as deprecated and will log if used that they are deprecated. Deprecated components will eventually be removed form Apache NiFi (most removed in NiFi 2.0).
You'll also make note of any items in the release notes that state:
Moved <XYZ> to optional build profiles
This means that these components were removed from Apache NiFi.
These components can be added manually later by downloading the nars from the central maven repository and adding them to the NiFi lib directory if you need them still.
https://mvnrepository.com/artifact/org.apache.nifi
Make a back up of your flow.json.gz, nifi.properties, and optionally flow.xml.gz files before you upgrade.
Otherwise, I see no issues with upgrading from 1.22 -- > 1.28 directly.
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Thank you,
Matt
