Cannot post to a core in solr using SimplePostTool

It looks like gettingstarted core is not being created. Create 'gettingstarted' core with this command.

bin/solr create -c gettingstarted

Once the core is created bin/post -c gettingstarted docs/ command runs without any error.

As in @cheffe's comment, it turns out I was missing <requestHandler> name="/update" ...

I am a solr noob so I looked up requestHandlers's here. This tutorial was also helpful. In essense, I only added the following line in my solrconfig.xml file

<requestHandler name="/update" class="solr.UpdateRequestHandler" />