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Author: sentrivana

MIGRATION_GUIDE.md

@@ -25,7 +25,7 @@ Looking to upgrade from Sentry SDK 2.x to 3.x? Here's a comprehensive list of wh
 
 - Spans no longer have a `description`. Use `name` instead.
 - Dropped support for Python 3.6.
-- The `custom_sampling_context` parameter of `start_transaction` has been removed. Use `attributes` instead to set key-value pairs of data that should be accessible in the traces sampler.
+- The `custom_sampling_context` parameter of `start_transaction` has been removed. Use `attributes` instead to set key-value pairs of data that should be accessible in the traces sampler. Note that span attributes need to conform to the [OpenTelemetry specification](https://opentelemetry.io/docs/concepts/signals/traces/#attributes), meaning only certain types can be set as values.
 - The PyMongo integration no longer sets tags. The data is still accessible via span attributes.
 - The PyMongo integration doesn't set `operation_ids` anymore. The individual IDs (`operation_id`, `request_id`, `session_id`) are now accessible as separate span attributes.
 - `sentry_sdk.metrics` and associated metrics APIs have been removed as Sentry no longer accepts metrics data in this form. See https://sentry.zendesk.com/hc/en-us/articles/26369339769883-Upcoming-API-Changes-to-Metrics