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cargo / serde_json

serde_json

What changed in serde_json 1, from its official release notes, upgrade guides and advisories. Sources checked 2026-11-15.

6 breaking3 behavior and defaults3 fixes and other

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serde_json 112 changes

Breaking changes 6

  • Formatter trait methods now return io::Result instead of serde_json::Result.

    1.0.0release notes

  • The method now receives &str instead of &[u8].

    1.0.0release notes

  • The conversion implementation was removed; serde_json::Error is intended to be constructed by serde_json.

    1.0.0release notes

  • Deserializing from this iterator type is no longer supported; use serde_json::from_reader instead.

    1.0.0release notes

  • Now supports only arrays and objects, rather than any JSON value.

    1.0.0release notes

  • The trait was removed; use serde_json::to_value instead.

    1.0.0release notes

Behavior and default changes 3

  • The preserve_order feature is supported in no_std builds.

    1.0.154release notes

  • The writer argument is now passed by value; passing &mut W continues to work.

    1.0.0release notes

  • Supports efficiently and safely deserializing borrowed data.

    1.0.0release notes

Fixes and other changes 3

  • Reports invalid UTF-8 at the first bad byte, helping developers locate the error.

    1.0.153release notes

  • Preserves the sign of -0 in arbitrary_precision mode.

    1.0.152release notes

  • Fixes comparison of large non-integer values with f32::INFINITY.

    1.0.152release notes