"As a part of the upgrade process, you should ensure that all changes from the defaults are re-applied to the instance for correct operation." - Does this mean restarting the confluence process (stop-confluence.sh and start-confluence.sh)?

[eddyah]

This question is in reference to Atlassian Documentation: After upgrading Confluence, you are unable to create new pages or spaces

As mentioned in the title above. Having issues with NGINX as a reverse proxy and now I'm unable to edit or create any pages without the 'forever loading' picture.

[Nic Brough -Adaptavist-]

You would not have had confluence running when you started the upgrade.  However if the upgrade has overwritten any changes you made to the old installation, then yes, you will need to stop confluence, re-apply them, and restart it.