bevyengine/bevy · error · GltfError

binary blob is missing

Error message

binary blob is missing

What it means

Raised in load_buffers (loader/mod.rs:1953-1958) when a buffer entry reports gltf::buffer::Source::Bin (JSON buffer with no "uri", i.e. buffer 0 of a GLB meant to live in the BIN chunk) but gltf.blob is None. In practice: the JSON declares the binary buffer while the loaded file carries no BIN chunk — typical when a .gltf JSON was extracted from a GLB without its binary, or the BIN chunk header says length 0.

Source

Thrown at crates/bevy_gltf/src/loader/mod.rs:96

use crate::convert_coordinates::GltfConvertCoordinates;

/// Must match [`MAX_JOINTS`](https://docs.rs/bevy/latest/bevy/pbr/constant.MAX_JOINTS.html)
pub const MAX_JOINTS: usize = 256;

/// An error that occurs when loading a glTF file.
#[derive(Error, Debug)]
pub enum GltfError {
    /// Unsupported primitive mode.
    #[error("unsupported primitive mode")]
    UnsupportedPrimitive {
        /// The primitive mode.
        mode: Mode,
    },
    /// Invalid glTF file.
    #[error("invalid glTF file: {0}")]
    Gltf(#[from] gltf::Error),
    /// Binary blob is missing.
    #[error("binary blob is missing")]
    MissingBlob,
    /// Decoding the base64 mesh data failed.
    #[error("failed to decode base64 mesh data")]
    Base64Decode(#[from] base64::DecodeError),
    /// Unsupported buffer format.
    #[error("unsupported buffer format")]
    BufferFormatUnsupported,
    /// The buffer URI was unable to be resolved with respect to the asset path.
    #[error("invalid buffer uri: {0}. asset path error={1}")]
    InvalidBufferUri(String, ParseAssetPathError),
    /// Invalid image mime type.
    #[error("invalid image mime type: {0}")]
    #[from(ignore)]
    InvalidImageMimeType(String),
    /// Error when loading a texture. Might be due to a disabled image file format feature.
    #[error("You may need to add the feature for the file format: {0}")]
    ImageError(#[from] TextureError),
    /// The image URI was unable to be resolved with respect to the asset path.

View on GitHub (pinned to 396ca72708)

Solutions

1. Re-export as a self-contained .glb so JSON and BIN chunk ship together.
2. Or keep the .gltf and give the buffer an explicit "uri": "model.bin" pointing at the extracted binary.
3. Validate with gltf-validator: it flags BUFFER_MISSING_URI / empty BIN chunk mismatches.

Example fix

// model.gltf (before)
"buffers": [{ "byteLength": 1024 }]
// after: external .bin next to the model
"buffers": [{ "byteLength": 1024, "uri": "model.bin" }]

fn buffer_needs_missing_blob(json: &serde_json::Value, is_glb: bool) -> bool {
    let buffers = json["buffers"].as_array();
    !is_glb
        && buffers.is_some_and(|bs| {
            bs.first().is_some_and(|b| b.get("uri").is_none())
        })
}

match err {
    GltfError::MissingBlob => {
        error!("JSON references a GLB BIN chunk that is absent; re-export as .glb or add a buffer uri");
    }
    other => return Err(other.into()),
}

When it happens

Trigger: A plain .gltf whose buffers[0] omits "uri" (spec allows this only inside GLB); a GLB whose BIN chunk is missing or zero-length while buffers[0] still has no uri; hand-authored JSON copied from a GLB export.

Common situations: Splitting a GLB into .gltf + assets by hand, minifiers that drop the BIN chunk reference incorrectly, truncated downloads of .glb files.

Related errors

• failed to decode base64 mesh data
• unsupported buffer format
• invalid buffer uri: {0}. asset path error={1}
• failed to read bytes from an asset path: {0}
• unsupported primitive mode

AI-assisted analysis of bevyengine/bevy@396ca72708 (2026-08-20). Data as JSON: /api/errors/5b0fc4f9b1b8a4fd. Report an issue: GitHub.