How to use the free Sentry error tracking service with Plone

And a follow up post,

How to add a Sentry user feedback dialog to Plone error pages

customize Plone to use Sentry's user feedback feature

Sentry.io includes a feature that pops up a nice looking dialog box to ask the user for more information (their name, email address, and what they were doing or trying to do) when an error occurs in your software. (Read more in the Sentry blog post or in the Sentry user documentation.)