People often encounter version mismatches between the H2O R/Python client and the H2O back-end.
This prevents you from successfully connecting to the H2O instance.
The error message looks like this from R:
In this case, the issue is that the R package for H2O is using 22.214.171.124 but the H2O back-end instance is running software version 126.96.36.199. They must have identical versions.
First, shut down your H2O cluster using the h2o.shutdown() command (in Python or R), or kill the Java process directly. You will need to kill the H2O instance so that you can install a new version.
You have three options:
1. Upgrade both to the latest version. (Recommended)
2. Upgrade the client package for H2O to the same version the server is running.
3. Upgrade the server version of H2O to the same version the client is running.
To install a new version of H2O, go here to download the latest stable version of H2O. Select the appropriate tab for your use case ("Install in R" vs "Install in Python", etc) and follow the commands to install the latest stable version of H2O.
The current stable release of H2O is always available here.
Please note that we cannot move models from version to version so you will have to keep using the version of H2O that you built your model in, or rebuild your model in the newer release.
Also, if you see the version mismatch error (in both R and Python upon running h2o.init()), and you already have an H2O cluster running, you should kill that cluster. You can do this either by using h2o.shutdown(), or by killing the background Java process from your Activity Monitor on Mac/the top command on Linux.