Failure to save when editing long pages

When editing some very long pages, Confluence does not save the page, and instead reloads the original content in the editor, with no error message displayed.

Sometimes a conflict is created, but the conflict can not be discarded or edited (error page: it either does not exist or you do not have access to it). The conflict can however, be viewed in View Changes mode.

Steps to reproduce

1. Create page
2. Enter long text
3. Save page
4. Edit page
5. Change text
6. Try to save again
(hangs)

NB: The issues seem to mainly arise when the long page content is saved on the Rich Text tab. For pages experiencing this issue, always save on the Wiki Markup tab.