What causes "Failed to execute ${path} --version." in rust-lang/rust?

Run the resolved path manually in a terminal: '/path/to/rust-analyzer --version' to see the actual OS-level error (missing .so, permission denied, exec format error).

rust-lang/rust · critical · Error

Failed to execute ${path} --version.

Error message

Failed to execute ${path} --version.

What it means

Thrown by bootstrap() at line 24-31 after isValidExecutable() returns false. isValidExecutable() spawns the resolved server binary with ['--version'] using the merged process + serverExtraEnv, and returns true only when the child exits with status 0. A false return means the binary was found but could not be executed successfully. When serverPath was explicitly set, the error appends guidance to remove or fix that config.

Source

Thrown at src/tools/rust-analyzer/editors/code/src/bootstrap.ts:25

import { TextDecoder } from "node:util";

export async function bootstrap(
    context: vscode.ExtensionContext,
    config: Config,
    state: PersistentState,
): Promise<string> {
    const path = await getServer(context, config, state);
    if (!path) {
        throw new Error(
            "rust-analyzer Language Server is not available. " +
                "Please, ensure its [proper installation](https://rust-analyzer.github.io/book/installation.html).",
        );
    }

    log.info("Using server binary at", path);

    if (!isValidExecutable(path, config.serverExtraEnv)) {
        throw new Error(
            `Failed to execute ${path} --version.` +
                (config.serverPath
                    ? `\`config.server.path\` or \`config.serverPath\` has been set explicitly.\
            Consider removing this config or making a valid server binary available at that path.`
                    : ""),
        );
    }

    return path;
}
async function getServer(
    context: vscode.ExtensionContext,
    config: Config,
    state: PersistentState,
): Promise<string | undefined> {
    const packageJson: {
        version: string;
        releaseTag: string | null;

View on GitHub (pinned to 7088e4b63a)

Solutions

Run the resolved path manually in a terminal: '/path/to/rust-analyzer --version' to see the actual OS-level error (missing .so, permission denied, exec format error).
Fix execute permissions: 'chmod +x /path/to/rust-analyzer'.
If the binary is the wrong architecture, reinstall or rebuild it for the host platform (rustup component add rust-analyzer, or rustup update).
Remove the explicit 'rust-analyzer.server.path' setting so the extension falls back to its bundled or PATH-resolved binary.
Check serverExtraEnv settings for environment variables that break the binary's runtime (e.g. LD_LIBRARY_PATH pointing at wrong libs).

Example fix

// before: serverPath points at a broken/wrong-arch binary
// settings.json
{ "rust-analyzer.server.path": "/home/user/old-build/ra" }
// after: remove the setting to use bundled binary
// (delete the key) or
{ "rust-analyzer.server.path": "/home/user/.cargo/bin/rust-analyzer" }

Defensive patterns

Strategy: validation

Validate before calling

import { isValidExecutable } from './bootstrap';

// Pre-check before relying on a server path
const valid = await isValidExecutable(candidatePath, config.serverExtraEnv);
if (!valid) {
  // Show actionable guidance before bootstrap throws
  vscode.window.showWarningMessage(
    `rust-analyzer binary at ${candidatePath} is not executable. Check permissions and architecture.`
  );
}

Try / catch

try {
  const serverPath = await bootstrap(context, config, state);
  // proceed
} catch (e) {
  if (e.message.includes('Failed to execute') && e.message.includes('--version')) {
    // Specific: binary found but won't run
    log.error('Server binary exists but is not executable/compatible', e);
  }
  throw e;
}

Prevention

After setting serverPath, test it manually: run the binary with --version in a terminal.
Ensure the binary has execute permission (chmod +x).
Verify the binary matches the host architecture (uname -m vs file <binary>).
Keep serverExtraEnv minimal — avoid LD_LIBRARY_PATH or DYLD_* overrides unless necessary.

When it happens

Trigger: isValidExecutable(path, config.serverExtraEnv) returns false at bootstrap.ts:24. Specifically: spawnAsync(path, ['--version'], {env}) at line 213 returns a result whose res.status !== 0 (line 222). This covers: the binary exists but is not executable (permissions), has an incompatible architecture (e.g. x86 binary on ARM), has missing shared libraries, is a Windows .exe on Linux or vice versa, or the --version invocation crashes/exits non-zero.

Common situations: Configuring serverPath to a binary built for a different OS/arch; missing execute permission bit after a manual copy; corrupted or partially-built binary; mismatched dynamic linker (especially on non-NixOS systems with custom lib paths); a stale serverPath pointing at an old or broken build after an upgrade.

Related errors

AI-assisted analysis of rust-lang/rust@7088e4b63a (2026-08-10). Data as JSON: /api/errors/6c10eac7322461e4. Report an issue: GitHub.