Recently upgraded to Confluence 8.5.5 (test environment)
Tested a few pages, in the Page Tree - when clicked on opens the new page and comes with the error page.

If the Page Tree is removed from side bar, and then access the page, able to open it and see the contents fine.
- Tried the space and site re-indexing - didnt helped
- Reindexed the database - didn't helped either
- Removed and re-added the page tree (from Space Tools > Configure side bar) - didn't worked.
- From Space Settings > Content Tools > Reorder Pages - able to access the pages from there
Anyone had similar issue and was able to get it resolved?
Only happening with a few pages in one of the space. Appreciate any suggestions you may have!