Forum OpenACS Q&A: Response to AOLserver won't start
Error in include template "/var/www/openacs/packages/openacs-bootstrap3-theme/resources/templates/packages/forums/lib/search/search-form": can't read "form:id": no such variable
Check the stacksize in your tcl config file. There are two places in the sample config where it is listed. It has to be at least 500000 for OpenACS 4. I ran into this problem myself.