When you initialize H2O in R or python as below:
You may see the following error:
Error in h2o.init(nthreads = -1) : Version mismatch! H2O is running version 184.108.40.206999 but h2o-R package is version 220.127.116.11.
This is a developer build, please contact your developer
You are seeing this error is because R is trying to connect an existing running H2O instance instead of the starting a new instance based on your R package.
If you look for H2O running in your environment you will find one. You can also try to following command to see running h2o process
$ ps -ef | grep h2o
Now if you turn off running H2O instance, and re-run the above command you will see a new instance of H2O is started.
The other option is to disable the strict version check of a running H2O instance and just connect with it as below (You can disable version checking on both R and python):
> h2o.init(strict_version_check = FALSE)