I discovered that the Links widget, for whatever reason, was failing—and being the very last widget rendered on my site, I didn’t notice it missing, somehow. Removing the links widget got the footer back in there, but not AJAX. So, now I’m seeing two issues! Links widget doesn’t work, nor does AJAX.
Not resolved for me! I updated K2 to the RC7.4 nightly, and am still having this error. The problem seems to be related to another error that I’m now having: Almost none of the pages (in the HTML sense) on my site load completely; the footer template doesn’t seem to load anymore, leaving a bunch of tags open. Only Pages (in the wp sense) with sidebarless=yes set (i.e., that don’t display the sidebars) load the footer, but of course without the sidebar, I can’t test whether AJAX search is working.
