Suddenly, I am having 403 errors returned when I try to save a (very) few Wiki pages when in the editor. It is consistent in that it will not save specific pages. I own the pages and have permission to edit. Also, getting a 406 error when trying to create a new page. This has been newly introduced with no upgrade done in the mean time. I cleared caches. Have not made any other installation changes (that I can tell or am aware of).
The hosting provider was running some scripts last week through the directories that incorrectly messed with some other installations (some XML page index generator being added for Google web crawler benefit on Wordpress installations that was incorrectly doing its magic in non-Wordpress install directories).
Any thoughts on causes or even how to debug the cause? The error pages are non-descriptive. Running v18.2 because I do not want to upgrade when still in this unknown state of operation.