This exception occurs often and intermittently when in development mode, and appears to get triggered by model associations. Does There are lots of references found by google but none seem to help to trace the problem to an offending class. Does anyone have any insight into how to trace the occurrence of this exception to it's cause? I've seen the posts on adding "unloadable" but I'm not sure I buy it--unless there's a way to trace it somehow to its cause. I'm not in favor of indiscriminately adding such things to every class in hopes the problem might go away. Rails 2.3.5.