bevyengine/bevy · error · ApplyError

attempted to apply type with {from_size} size to a type with

Error message

attempted to apply type with {from_size} size to a type with {to_size} size

What it means

ApplyError::DifferentSize — try_apply on array-like values (arrays/lists) found differing element counts, e.g. applying [u8; 4] onto [u8; 3]. Payloads: from_size and to_size. Source and destination must have equal sizes.

Source

Thrown at crates/bevy_reflect/src/reflect.rs:50

    #[error("enum variant `{variant_name}` doesn't have a field named `{field_name}`")]
    /// Enum variant that we tried to apply to was missing a field.
    MissingEnumField {
        /// Name of the enum variant.
        variant_name: Box<str>,
        /// Name of the missing field.
        field_name: Box<str>,
    },

    #[error("`{from_type}` is not `{to_type}`")]
    /// Tried to apply incompatible types.
    MismatchedTypes {
        /// Type of the value we attempted to apply.
        from_type: Box<str>,
        /// Type we attempted to apply the value to.
        to_type: Box<str>,
    },

    #[error("attempted to apply type with {from_size} size to a type with {to_size} size")]
    /// Attempted to apply an [array-like] type to another of different size, e.g. a [u8; 4] to [u8; 3].
    ///
    /// [array-like]: crate::array::Array
    DifferentSize {
        /// Size of the value we attempted to apply, in elements.
        from_size: usize,
        /// Size of the type we attempted to apply the value to, in elements.
        to_size: usize,
    },

    #[error("variant with name `{variant_name}` does not exist on enum `{enum_name}`")]
    /// The enum we tried to apply to didn't contain a variant with the give name.
    UnknownVariant {
        /// Name of the enum.
        enum_name: Box<str>,
        /// Name of the missing variant.
        variant_name: Box<str>,
    },

View on GitHub (pinned to 396ca72708)

Solutions

1. Ensure both array-like values have the same length
2. Truncate or pad the source data to the target's length before applying

When it happens

Trigger: Thrown at crates/bevy_reflect/src/reflect.rs:50 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of bevyengine/bevy@396ca72708 (2026-08-20). Data as JSON: /api/errors/8691ccae170de516. Report an issue: GitHub.