If the Puppet Enterprise console is overloaded, it can trigger an OutOfMemory error and crash. I see this most often when spinning up small Puppet Enterprise installations on a virtual machine or container on my local laptop. When the console is down, Puppet Enterprise users will receive an error, letting them know that the node manager service isn't running. Users should check the status of the PE console and the relevant logs if this message starts to come up in agent runs:

[root@wordpress ~]# puppet agent -t
Warning: Unable to fetch my node definition, but the agent run will continue:
Warning: Error 500 on SERVER: Server Error: Classification of wordpress failed due to a Node Manager service error. Please check /var/log/puppetlabs/console-services/console-services.log on the node(s) running the Node Manager service for more details.
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Retrieving locales
Info: Loading facts
Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Failed when searching for node wordpress: Classification of wordpress failed due to a Node Manager service error. Please check /var/log/puppetlabs/console-services/console-services.log on the node(s) running the Node Manager service for more details.

Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run