How to upgrade the WebForm module? I'm planning on upgrading the WebForm module in my Drupal 7 site. The current WebForm version is 7.x-3.19 and I'm upgrading to 7.x-4.2. 

Question: Is it as simple as uploading the new version? Do I need to run update.php afterwards?

Somehow I seem to remember that updating the WebForm module is not as simple as other modules and can cause existing webforms to break.
You should be fine with the upgrade.  Back up your DB, of course.  If you are uploading the module instead of installing through the UI, then yes, you need to run /update.php.