In WP Admin, under "Appearance" and then "Theme Settings", when I choose to save theme settings, I get a 404 error. I very recently saved changes to my theme settings with no problem; this just started occurring. I can't think of any changes I've made that might cause this and am at a roadblock troubleshooting it myself.
More details: From here:
Clicking to save takes me out of WP Admin and to the site, where there is a 404 error. Strangely, the URL remains the same:
When I refresh the page, it stays where it is, on my site with the 404 error. But if I copy and paste that URL into a new window, or even the same window in my browser, it returns me to the theme settings page in WP Admin, which remain as they were, attempted changes unsaved.
I'm using multiple installations of WordPress. This is suddenly occurring in every single instance (3 of them), even though I haven't done anything to 2 of them for some time, well before I noticed this problem occurring (as I mentioned, just a week or so ago I saved theme settings with no problems). My main site is in the root folder. I have additional sites in subdomain folders. This problem now occurs with all of them, including my main site.
I've tried creating a brand new subdomain. I then did a fresh install of the WordPress 2.9.2. Starting from scratch. I then installed a theme I know has theme setting options. It saves fine in the fresh installation. It's only my previous installations that are broken somehow.
Any assistance would be appreciated!