bevyengine/bevy · error · ReflectPathError

Encountered an error at offset {offset} while parsing `{path

Error message

Encountered an error at offset {offset} while parsing `{path}`: {error}

What it means

ReflectPathError::ParseError wraps a lower-level path-parser failure: it reports the byte offset in the path string, the full path, and the nested ParseError (NoIdent, ExpectedIdent, InvalidIndex, Unclosed, BadClose, CloseBeforeOpen). It is returned whenever a reflect path string like "a.b[0].c" violates the grammar (identifiers separated by '.', indices in '[]').

Source

Thrown at crates/bevy_reflect/src/path/mod.rs:33

use derive_more::derive::From;
use thiserror::Error;

type PathResult<'a, T> = Result<T, ReflectPathError<'a>>;

/// An error returned from a failed path string query.
#[derive(Error, Debug, PartialEq, Eq)]
pub enum ReflectPathError<'a> {
    /// An error caused by trying to access a path that's not able to be accessed,
    /// see [`AccessError`] for details.
    #[error(transparent)]
    InvalidAccess(AccessError<'a>),

    /// An error that occurs when a type cannot downcast to a given type.
    #[error("Can't downcast result of access to the given type")]
    InvalidDowncast,

    /// An error caused by an invalid path string that couldn't be parsed.
    #[error("Encountered an error at offset {offset} while parsing `{path}`: {error}")]
    ParseError {
        /// Position in `path`.
        offset: usize,
        /// The path that the error occurred in.
        path: &'a str,
        /// The underlying error.
        error: ParseError<'a>,
    },
}

impl<'a> From<AccessError<'a>> for ReflectPathError<'a> {
    fn from(value: AccessError<'a>) -> Self {
        ReflectPathError::InvalidAccess(value)
    }
}

/// Something that can be interpreted as a reflection path in [`GetPath`].
pub trait ReflectPath<'a>: Sized {

View on GitHub (pinned to 396ca72708)

Solutions

1. Use the reported offset and nested ParseError to fix the exact spot in the path string; valid syntax is ident('.'ident|'['index']')*.
2. Validate/normalize path strings before use (e.g. Path::parse on a known-good subset) when they come from users or files.
3. For alternate syntaxes, translate them into reflect-path syntax before querying.
4. If the path is dynamic, prefer building access programmatically (Struct::field, List::get) instead of string parsing.

Example fix

// before
let v = entity.path::<f32>("transform..scale"); // ParseError at offset 10

// after
let v = entity.path::<f32>("transform.scale");

use bevy_reflect::path::Path;

fn valid_path(s: &str) -> bool {
    Path::parse(s).is_ok() // reject bad strings before any query
}

match entity.reflect_path(user_path) {
    Ok(el) => { /* ... */ }
    Err(ReflectPathError::ParseError { offset, path, error }) => {
        warn!("bad path '{path}' at offset {offset}: {error}");
    }
    Err(other) => warn!("path failed: {other}"),
}

When it happens

Trigger: Passing a malformed path string to GetPath::path/reflect_path APIs — unclosed brackets, stray tokens, empty identifiers, or non-integer indices; the offset field points at where parsing stopped.

Common situations: Paths assembled from user input, config files, or query DSLs; typos like "foo[0" or "foo..bar"; JSON-style paths ("a.b[0]") vs alternate syntaxes people assume ("a->b", "a/b") that the parser rejects.

Related errors

• expected an identifier, but reached end of path string
• expected an identifier, got '{0}' instead
• failed to parse index as integer
• Attempted to insert invalid value of type {}.
• Attempted to push invalid value of type {}.

AI-assisted analysis of bevyengine/bevy@396ca72708 (2026-08-20). Data as JSON: /api/errors/b2dab958b54c4135. Report an issue: GitHub.