Wrong Minecraft version

Crash on World Load: NoClassDefFoundError: net/coderbot/iris/Iris

What the log looks like

java\.lang\.NoClassDefFoundError: net/coderbot/iris/Iris
java\.lang\.ClassNotFoundException: net\.coderbot\.iris\.Iris

How to fix it

  1. Check the first 'at ...' line directly underneath 'java.lang.NoClassDefFoundError: net/coderbot/iris/Iris' in your crash report to identify the outdated mod (for example, 'com.qendolin.betterclouds' means Better Clouds).
  2. Update that mod (and its required libraries, such as YACL for Better Clouds) to a newer release that supports Iris 1.7 or above.
  3. Verify that both Iris and Sodium are updated to matching versions for your exact Minecraft version.
  4. If the offending mod has not been updated for Iris 1.7+ yet, either remove that mod from your 'mods' folder or downgrade Iris and Sodium to an older Iris 1.6.x compatible pair.
LoadersFabric, Quilt, Neoforge
SeverityStops the game
CategoryWrong Minecraft version

Check your own log

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