helix-editor/helix · error

No debug adapter available for language

Error message

No debug adapter available for language

What it means

dap_start_impl (commands/dap.rs) resolves the current document's language config and requires a `debugger` section (with templates) from languages.toml: doc.language_config().and_then(|c| c.debugger.as_ref()). A scratch/unnamed buffer, an unrecognized file type, or a language whose entry has no debugger configuration makes this None, so :debug-start/:debug-remote fail before any adapter process is spawned. A separate workspace-trust bail fires earlier if the workspace is untrusted.

Source

Thrown at helix-term/src/commands/dap.rs:137

    socket: Option<std::net::SocketAddr>,
    params: Option<Vec<std::borrow::Cow<str>>>,
) -> Result<(), anyhow::Error> {
    // Refuse to spawn a debug adapter in workspace trust restricted mode.
    let workspace = doc!(cx.editor).workspace_root().to_path_buf();
    if !cx
        .editor
        .workspace_trust
        .query(&workspace, helix_loader::workspace_trust::TrustQuery::Dap)
        .is_trusted()
    {
        bail!("Workspace is not trusted. Run `:workspace-trust` to enable the debug adapter.");
    }

    let doc = doc!(cx.editor);
    let config = doc
        .language_config()
        .and_then(|config| config.debugger.as_ref())
        .ok_or_else(|| anyhow!("No debug adapter available for language"))?;

    let id = cx
        .editor
        .debug_adapters
        .start_client(socket, config)
        .map_err(|e| anyhow!("Failed to start debug client: {}", e))?;

    // TODO: avoid refetching all of this... pass a config in
    let template = match name {
        Some(name) => config.templates.iter().find(|t| t.name == name),
        None => config.templates.first(),
    }
    .ok_or_else(|| anyhow!("No debug config with given name"))?;

    let mut args: HashMap<&str, Value> = if let Some(params) = params.as_ref() {
        let preprocessed_params = prepare_dap_params(template, params);
        template
            .args

View on GitHub (pinned to 079a789e8c)

Solutions

1. Run `hx --health <lang>` — it shows the configured debug adapters; no adapter listed means no DAP config exists.
2. Add a `[language.debugger]` block with at least one `[[language.debugger.templates]]` entry to your languages.toml override for that language.
3. Make sure the buffer is recognized: `:set-language <lang>` for a scratch file, or open the real file from disk.

Example fix

# ~/.config/helix/languages.toml — after (before: no debugger block)
[language.debugger]
command = "lldb-dap"
transport = "stdio"
[[language.debugger.templates]]
name = "binary"
request = "launch"

let has_dap = doc
    .language_config()
    .and_then(|c| c.debugger.as_ref())
    .map(|d| !d.templates.is_empty())
    .unwrap_or(false);
if !has_dap { /* skip :debug-start, show hint instead */ }

fn has_debugger(doc: &helix_view::Document) -> bool {
    doc.language_config()
        .and_then(|c| c.debugger.as_ref())
        .is_some()
}

When it happens

Trigger: `:debug-start` in a new scratch buffer, a Markdown/log file, or a language whose languages.toml entry has no [language.debugger] block — most languages ship none by default.

Common situations: Assuming IDE-style debugging works out of the box; forgetting that DAP configs are per-language and largely user-supplied; running the command in a buffer whose file type was not detected.

Related errors

• Command not provided
• Incorrect transport {}
• DAP request failed
• Failed to start debug client: {}
• No debug config with given name

AI-assisted analysis of helix-editor/helix@079a789e8c (2026-08-16). Data as JSON: /api/errors/86989fdb1368cc6e. Report an issue: GitHub.