Kuberwastaken/claurst · error · anyhow::Error

No LSP server configured for

Error message

No LSP server configured for '{}'

What it means

Thrown in `LspManager::hover` when `server_name_for_file(file_path)` returns `None` — no registered LSP server config claims the file's language/extension. The manager refuses to start any server because it does not know which one would handle this file.

Solutions

1. Register a server config covering the file's language via seed_from_config / register_server before calling hover.
2. Check settings so the file's extension is listed in the appropriate server's languages/extensions.
3. Skip LSP features gracefully for unconfigured file types instead of propagating the error.
4. Verify server_name_for_file's matching logic against the actual file name/extension.

Example fix

// before: hover on any file, erroring on unconfigured types
let hover = manager.hover(path, root, line, col).await?;
// after: only when a server is configured for the type
if manager.server_name_for_file(path).is_some() {
    let hover = manager.hover(path, root, line, col).await?;
}

// pre-check before hover
if manager.server_name_for_file(path).is_none() {
    return Ok(None); // no server configured for this file type
}

fn has_lsp_server(manager: &LspManager, path: &str) -> bool {
    manager.server_name_for_file(path).is_some()
}

let hover = manager.hover(path, root, line, col).await
    .or_else(|e| {
        if e.to_string().starts_with("No LSP server configured") { Ok(None) } else { Err(e) }
    })?;

When it happens

Trigger: hover(file_path, root_dir, line, character) called with a file extension (or language id) not covered by any registered LspServerConfig (see register_server / seed_from_config).

Common situations: Requesting hover on a file type like .txt, .json, or a new extension the user hasn't configured; LSP servers section missing from settings; language mapping typo in config (e.g. `rs` vs `rust` extensions).

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Failed to start LSP server
• LSP server stdin not available
• LSP server stdout not available
• LSP client already shut down
• LSP request ' ' timed out (server: )

AI-assisted analysis of Kuberwastaken/claurst@b0637c97ec (2026-09-10). Data as JSON: /api/errors/883807c39658da23. Report an issue: GitHub.

Appendix: source

Thrown at src-rust/crates/core/src/lsp.rs:1110

            if !self.configs.iter().any(|c| c.name == cfg.name) {
                self.register_server(cfg.clone());
            }
        }
    }

    /// Get hover information for `file_path` at the given 1-based position.
    pub async fn hover(
        &mut self,
        file_path: &str,
        root_dir: &Path,
        line: u32,
        character: u32,
    ) -> anyhow::Result<Option<String>> {
        let uri = path_to_uri(file_path);
        let server_name = self
            .server_name_for_file(file_path)
            .ok_or_else(|| {
                anyhow::anyhow!("No LSP server configured for '{}'", file_path)
            })?
            .to_string();
        self.ensure_started(file_path, root_dir).await?;
        let client = self
            .clients
            .get(&server_name)
            .ok_or_else(|| anyhow::anyhow!("LSP server '{}' not running", server_name))?;
        client.hover(&uri, line, character).await
    }

    /// Get definition locations for `file_path` at the given 1-based position.
    pub async fn definition(
        &mut self,
        file_path: &str,
        root_dir: &Path,
        line: u32,
        character: u32,
    ) -> anyhow::Result<Vec<String>> {

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