E0063: missing field in initializer of struct Rust Origin: Application & API OSI layer 7 · Application Last updated 5 Nov 2026

Rust: error[E0063]: missing field `age` in initializer of `User`

A struct literal doesn't set all fields.

Exact message you may see error[E0063]: missing field `age` in initializer of `User`missing fields `age` and `email` in initializer of `User`error[E0063]: missing fieldE0063 missing field in initializer ofmissing field in initializer
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Seen on: Rust

Meaning

Provide every field, use struct update syntax (..Default::default()), or implement Default/a constructor. Added a new field to a struct? Update all literals. For optional values use Option<T>.

Common causes

  • New field added but not set in literals
  • Forgot a field
  • Constructing with fewer fields than the struct has
  • No Default available
  • Macro/derive-generated structs

⚡ Quick fix

  1. Set the missing field
  2. User { name, ..Default::default() } with #[derive(Default)]
  3. Add a new() constructor

Detailed fix by platform

Rust

  1. #[derive(Default)] struct User { name: String, age: u32 } let u = User { name: "A".into(), ..Default::default() };

How to diagnose

  1. Field — Missing which?
  2. Default — Derivable?
  3. Constructor — new()?

🔧 Still not fixed?

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Where this error sits

Origin: Application & API. Errors that are often confused with or caused by this one (click to open):

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