I see something related to front coding dictionaries

Druid 30 will read your Druid 25 segments without issue Front coding is something you have to deliberately set, and would only affect a rollback to older versions Scenario would be: you are running a version of Druid that supports front coding, you create segments that use front coding and you try to go back to a Druid version that does not support front coding

Thanks

One thing to note is that when upgrading to version 28 we had to add a column to the segments metadata. Kindly look into that

Thanks @Utkarsh Chaturvedi