Our Rails3 app is a modified version of a prior Rails3 app which did not cause IE7+ to give the dreaded "Object expected" error. And the new app doesn't throw that error when run locally either. But when we run the same code on heroku IE does report "Done, with errors on page" and specifically "Line 2, Char 1, Error: Object expected, URL (url for whatever page is viewed)"
Other than that things run fine.
Any thoughts why we see the errors only when remotely hosted?
solved. it turns out the issue was related to a missing js file that was being added to the header by default.