# Revision history [back]

The elements you give (Communication with the Sage server is failing., running this worksheet) let us infer that you are running a Jupyter notebook worksheet (or maybe a Sage notebook worksheet).

In this situation, your client (Jupyter or the Sage notebook) establishes a network connection (not necessarily an Internet connection...) with a local server (spawning one if necessary).

Depending on you platform (which you didn't state), there are a few ways this connection can be messed up ; how to fix it depends on the specifics of the trouble, which you gave us no way to diagnose or even divine...

What you can do (at least for a Jupyter notebook, I haven't used the Sage notebook in a long while) is :

• save your worksheet then close it ;

• close your client, then kill its server (C-c C-c in its terminal windows)

Post-scriptum : I see (a bit lately) that you have added the tag cocalc to your question. If this happens in a CoCalc session, the problem is internal to CoCalc : their client, which you access through the Internet, indeed), cant communicate with their server. What you should do in this case is to report the problem to CoCalc's staff : as far as I can tell, there is nothing you can do...