I have opened a notebook on the Bluemix Spark service (Enterprise Plan) and received the following error message:
What does this error mean?
You have already 10 Notebook kernels running at the same time. You need to stop one to start a new one:
On the Notebooks list (https://console.ng.bluemix.net/data/analytics), find Notebooks with a green circle (those are notebooks with a running Kernel). Then, click on the gear icon of such a notebook, and choose "Stop Kernel".
Reason: Kernels may continue running even if you close a notebook's user interface if there is still code being executed. In that case, you need to explicitly “Stop Kernel" as described.