Issue Summary

Attempting to turn ON the new Navigation for Confluence fails with an error:

We couldn't turn on the new navigation

Check your connection and try again

Steps to Reproduce

1. Access https://instance_url.atlassian.net/wiki/admin/newfeatures 
2. Attempt to turn ON the New navigation there.

Expected Results

The New navigation is turned ON successfully.

Actual Results

It fails with error:

We couldn't turn on the new navigation
Check your connection and try again 

Workaround

Contact the Atlassian Support team via https://support.atlassian.com/contact in order to turn the feature ON from the back-end as an alternative.