Jackson Release 2.20.1

Patch version of 2.20, released October 30, 2025.

Following fixes are included in this patch release.

Changes, core

Streaming

• #1473: Bug with Surrogates + Segments in the UTF8JsonGenerator

Databind

• #5292: MapperFeature.FIX_FIELD_NAME_UPPER_CASE_PREFIX does not work with Constructor parameters

Changes, data formats

Avro

• #601: Jackson subtype Avro schema unions are non-deterministic and therefore incompatible with each other

CBOR

• #599: (cbor) Unable to deserialize stringref-enabled CBOR with ignored properties
• #616: CBOR text gets truncated on decoding

Ion

• #623: (ion) Upgrade ion-java dep to 1.11.11 (from 1.11.10)