xai-org/grok-build · error · io::Error

unsupported version: {}

Error message

unsupported version: {}

What it means

After the magic header, read_from reads a little-endian u16 version field and requires it to equal the VERSION constant the library currently writes. Any other version means the on-disk format is incompatible and it fails with io::ErrorKind::InvalidData, 'unsupported version: <n>'.

Source

Thrown at crates/codegen/xai-grok-workspace/src/file_system/index.rs:911

        Self::read_from(&mut io::Cursor::new(data))
    }

    /// Read from a reader in binary format.
    pub fn read_from<R: Read>(r: &mut R) -> io::Result<Self> {
        // Header
        let mut magic = [0u8; 4];
        r.read_exact(&mut magic)?;
        if &magic != MAGIC_INDEX {
            return Err(io::Error::new(io::ErrorKind::InvalidData, "invalid magic"));
        }

        let mut buf2 = [0u8; 2];
        let mut buf4 = [0u8; 4];

        r.read_exact(&mut buf2)?;
        let version = u16::from_le_bytes(buf2);
        if version != VERSION {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                format!("unsupported version: {}", version),
            ));
        }

        r.read_exact(&mut buf2)?;
        let flags = u16::from_le_bytes(buf2);

        // Handle compression
        if flags & FLAG_COMPRESSED != 0 {
            #[cfg(feature = "compression")]
            {
                r.read_exact(&mut buf4)?;
                let _n_segs = u32::from_le_bytes(buf4);
                r.read_exact(&mut buf4)?;
                let _n_entries = u32::from_le_bytes(buf4);

                let mut compressed = Vec::new();

View on GitHub (pinned to bc7f02eddd)

Solutions

1. Regenerate the index with the current library version (delete the stale file and rebuild).
2. Use a library version matching the file's version to read the old index, then re-save it.
3. Check the version bytes in the file and migrate the data if a migration path exists.

Example fix

// before
let idx = Index::read_from(&mut file)?;
// after
let idx = match Index::read_from(&mut file) {
    Ok(i) => i,
    Err(e) if e.to_string().starts_with("unsupported version") => {
        std::fs::remove_file(&index_path)?; // stale format
        Index::rebuild(&workspace_root)?
    }
    Err(e) => return Err(e.into()),
};

fn read_version(path: &std::path::Path) -> std::io::Result<Option<u16>> {
    use std::io::Read;
    let mut f = std::fs::File::open(path)?;
    f.seek(std::io::SeekFrom::Start(4))?;
    let mut b = [0u8; 2];
    if f.read_exact(&mut b).is_err() { return Ok(None); }
    Ok(Some(u16::from_le_bytes(b)))
}
// if Some(v) and v != VERSION -> regenerate before loading

match Index::read_from(&mut file) {
    Ok(i) => i,
    Err(e) if e.to_string().starts_with("unsupported version") => {
        std::fs::remove_file(&index_path)?;
        Index::rebuild(&workspace_root)?
    }
    Err(e) => return Err(e.into()),
}

When it happens

Trigger: Calling Index::read_from on an index file whose version field differs from VERSION — i.e. the file was written by an older or newer release of the library with a different binary layout.

Common situations: Upgrading or downgrading the library/workspace version while keeping the old index file on disk; copying an index between deployments built from different code versions.

Related errors

• Unsupported checkpoint schema version {schema_version}. Cann
• invalid magic
• invalid segment id
• Leader does not advertise capabilities (legacy version)
• No `version` field in plugin.json. Set a version to use `gro

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/773ca2bab16f0f65. Report an issue: GitHub.