Sentry uses breadcrumbs to create a trail of events that happened prior to an issue. These events are very similar to traditional logs, but can record more rich structured data.

This page provides an overview of manual breadcrumb recording and customization. Learn more about the information that displays on the Issue Details page and how you can filter breadcrumbs to quickly resolve issues in Using Breadcrumbs.

Manual Breadcrumbs

You can manually add breadcrumbs whenever something interesting happens. For example, you might manually record a breadcrumb if the user authenticates or another state change happens.

from sentry_sdk import add_breadcrumb

    message='Authenticated user %s' %,

The available breadcrumb keys are type, category, message, level, timestamp (which many SDKs will set automatically for you), and data, which is the place to put any additional information you'd like the breadcrumb to include. Using keys other than these six won't cause an error, but will result in the data being dropped when the event is processed by Sentry.

Automatic Breadcrumbs

SDKs and their associated integrations will automatically record many types of breadcrumbs. For instance, the browser JavaScript SDK will automatically record all location changes.

Customize Breadcrumbs

SDKs allow you to customize breadcrumbs through the before_breadcrumb hook. This hook is passed an already assembled breadcrumb and, in some SDKs, an optional hint. The function can modify the breadcrumb or decide to discard it entirely by returning null:

import sentry_sdk

def before_breadcrumb(crumb, hint):
    if crumb['category'] == 'a.spammy.Logger':
        return None
    return crumb


For information about what can be done with the hint, see Filtering Events.

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