Found it, sort of, here, in case search engines bring anyone else to this thread
http://wordpress.org/support/topic/caption-broken-in-new-34-posts?replies=43
The plugin hosted on the official site is still generating this error.
I was able to fix this by deleting line 271 in collapscatlist.php
$link2 .= apply_filters(‘single_cat_title’, $cat2->name);
Same problem here.
I updated the plugin to 0.5.2 through the wp-admin page, did not resolve the issue.
Cannot download it from your page, get a 404 error
