On composer update (production server) I get the following :
Generating autoload files [ErrorException] file_put_contents(/home/forge/default/bootstrap/cache/services.json): failed t o open stream: No such file or directory Script php artisan clear-compiled handling the post-update-cmd event returned wi th an error
Like seomike said, just create a folder under app_root/bootstrap directory and name it "cache". Then, just refresh the page and it will all work again.