If you are getting the following error when you try running validation for shard addition, then the issue is the indentation in the conf file. The conf files follow YAML format and they are quite pesky. Use YAML validator ( Looker for YAML “linters”) to ensure the indentation is fine.
Replica set ‘m103-repl’ not configured correctly - make sure each node is started with
a wiredTiger cache size of 0.1 GB. Your cluster will crash in the following lab
if you don’t do this!