rust-lang/cargo · error · anyhow::Error

failed to find a workspace root

Error message

failed to find a workspace root

What it means

Thrown by `inheritable` at src/workspace/parser/mod.rs:1003. When a package is configured as a workspace member with no explicit root (`WorkspaceConfig::Member { root: None }`) — i.e. it relies on workspace inheritance (`workspace = true` on a dependency or `[package] workspace = true`) — cargo walks up the tree via `find_workspace_root`. If no ancestor `Cargo.toml` defines a `[workspace]` table, inheritance cannot resolve and parsing fails.

Source

Thrown at src/workspace/parser/mod.rs:1003

    workspace_config: &WorkspaceConfig,
) -> CargoResult<InheritableFields> {
    match workspace_config {
        WorkspaceConfig::Root(root) => Ok(root.inheritable().clone()),
        WorkspaceConfig::Member {
            root: Some(path_to_root),
        } => {
            let path = normalized_path
                .parent()
                .unwrap()
                .join(path_to_root)
                .join("Cargo.toml");
            let root_path = paths::normalize_path(&path);
            inheritable_from_path(gctx, root_path)
        }
        WorkspaceConfig::Member { root: None } => {
            match find_workspace_root(&normalized_path, gctx)? {
                Some(path_to_root) => inheritable_from_path(gctx, path_to_root),
                None => Err(anyhow!("failed to find a workspace root")),
            }
        }
    }
}

fn inheritable_from_path(
    gctx: &GlobalContext,
    workspace_path: PathBuf,
) -> CargoResult<InheritableFields> {
    // Workspace path should have Cargo.toml at the end
    let workspace_path_root = workspace_path.parent().unwrap();

    // Let the borrow exit scope so that it can be picked up if there is a need to
    // read a manifest
    if let Some(ws_root) = gctx.ws_roots().get(workspace_path_root) {
        return Ok(ws_root.inheritable().clone());
    };

View on GitHub (pinned to 0e07a15537)

Solutions

1. Build from the workspace root that contains the `[workspace]` table, or ensure an ancestor dir has one.
2. Remove the `workspace = true` / inheritance markers and specify sources directly in the member.
3. Add a `[workspace]` section in the nearest appropriate ancestor manifest.

Example fix

# before (member, no root above it)
[dependencies]
foo = { workspace = true }
# after (self-contained)
[dependencies]
foo = "1.0"

use cargo::workspace::find_workspace_root;
if find_workspace_root(&manifest_path, gctx)?.is_none()
    && uses_inheritance(&manifest)? {
    return Err("no workspace root found for inherited fields".into());
}

When it happens

Trigger: A crate whose Cargo.toml uses `foo = { workspace = true }` or inherits `[package]` fields but is built standalone outside any workspace; moving a member out of its workspace without updating the manifest.

Common situations: Cloning a single sub-crate from a monorepo; vendoring a member without its root; CI building a path dependency that expects a parent workspace; deleted/renamed the root `Cargo.toml`.

Related errors

• dependency ({}) specified without providing a local path, Gi
• cannot override workspace dependency with `--default-feature
• cannot override workspace dependency with `--registry`, eith
• cannot override workspace dependency with `--rename`, either
• multiple packages found at `{src}`: {} To disambiguate,

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/6709f02018c180bc.json. Report an issue: GitHub.