PSA: Confluence will error if the page title contains square brackets - the result will be a page that cannot be navigated to and therefore cannot be edited or deleted (as far as I can tell).
I created a new page in my Confluence personal space and included square brackets in the title. The page that was published could not be navigated to, Apache Tomcat simply returned 400 errors saying that it could not fulfil my request.
Apparently this is a known issue and there is some documentation below.
https://confluence.atlassian.com/confkb/confluence-issues-with-special-characters-used-in-content-name-when-behind-a-proxy-1018788864.html
Luckily, I had just created a page right before this one. I noticed that the edit page button uses a page id to reference the page to be edited and after two attempts I was able to guess the page ID for the page I couldn’t access and was able to rename it - now it works fine.
I’m not sure how widely known this issue is, but figured I’d share my experience here in case it helps anyone.