Summarize this article in one sentence.
This message should only appear when you are attempting to update a game or app; system updates are not affected by your available system storage.  Open the "My games & apps" menu. Select a game, app, or trailer that you don't use anymore. Press the Menu button on your controller and select "Uninstall". Try updating again after freeing up some space. This is typically caused by network connection issues, and has been known to appear at any time before, during, or after an update.  Ensure that you are connected to Xbox Live and try updating again. If you still can't update, power down the Xbox One completely, and then unplug the power cable for about 30 seconds. Plug it back in and restart the Xbox One to retry the update. If you still can't download the update, try the Offline System Update Diagnostic Tool. This is a file that can be downloaded from Microsoft here, where you can also find detailed instructions for running it. You will need an NTFS-formatted USB drive with at least 2 GB of free space. Running the tool on your Xbox One will take a long time to complete.  If none of the above steps work for getting your console updated, you'll need to contact Microsoft to arrange a console repair.
I get an "Your Xbox is almost full" message when trying to update. I get a "There was a problem with the update" message.