Both major versions are built for Langfuse v4 and remove APIs that had already been deprecated.
The releases add experimentUrl and experiment_url links to experiment comparison views, dotted-path filtering of nested metadata such as a.b, gzip-compressed span batches, and batch score operations. Scores can now be created with api.scores.create and read with api.scores.get_many or api.scores.getMany, replacing api.scores_v3 and api.scoresV3. The leaner API client removes endpoints including api.legacy.* and api.ingestion.
Installation targets are langfuse>=5 for Python and version 6 of @langfuse/client, @langfuse/tracing, and @langfuse/otel for JS/TS. The SDKs require Langfuse Cloud or self-hosted Langfuse v4.59.0 or later, plus Python 3.11+ or Node.js 22+. Self-hosted v3 users must upgrade Langfuse before adopting them.
The source says most users should face a small version upgrade and provides migration guides. It does not establish the migration effort for any particular application, nor does it add numeric or boolean comparisons for metadata values, which remain stored as strings.