# v3.0.0

Released on 2017-12-17.

First 3.x release — a major release with breaking changes (see the
[migration guide](../../integration/migration_guide.md)).

- Introduces user-defined [exceptions](../exceptions.md) (`json::exception` and subtypes, each with an
  identifier).
- Adds a non-throwing [`accept`](../../api/basic_json/accept.md) function and an `allow_exceptions` flag
  for [`parse`](../../api/basic_json/parse.md), and an [`update`](../../api/basic_json/update.md) function to
  merge objects.
- Adds streaming for CBOR and MessagePack and allows storing NaN/infinity.
- Non-UTF-8 strings now throw on serialization, and the iterator category changed to bidirectional.

[Full release notes](https://github.com/nlohmann/json/releases/tag/v3.0.0).

## API changes

<!-- api-changes -->