oraios/serena · error · TimeoutError

Svelte companion TypeScript server did not become ready…

Error message

Svelte companion TypeScript server did not become ready within {timeout:.0f}s

What it means

SvelteLanguageServer overrides _handle_server_ready_timeout because its setup also depends on a companion TypeScript (tsserver) process. If the full server + companion pair doesn't signal readiness within the configured timeout, this TimeoutError is raised instead of the generic one, telling you the companion TS server in particular didn't become ready.

Solutions

Increase the server-ready timeout in the SolidLSP/LanguageServerConfig to accommodate cold starts.
Verify node and TypeScript are installed and that a manual `npx svelte-language-server` (and tsserver) starts cleanly.
Run once with the pre-warmed cache; subsequent starts are usually fast enough.
Check server logs for the companion TypeScript server crashing (missing typescript dependency in the workspace).

Example fix

// before
cfg = LanguageServerConfig("svelte", timeout=30)
// after
cfg = LanguageServerConfig("svelte", timeout=120)

Defensive patterns

Strategy: try-catch

Validate before calling

# ensure node/typescript and svelte LS resolvable before init
import shutil
assert shutil.which("node"), "Node.js required for Svelte + companion TypeScript server"

Type guard

def svelte_server_prereqs_ok() -> bool:
    import shutil
    return shutil.which("node") is not None and shutil.which("npm") is not None

Try / catch

try:
    server = SvelteLanguageServer(config, repo_root, settings)
    server.start()
except TimeoutError as e:
    if "did not become ready" in str(e):
        config.timeout = 120  # retry with a larger ready timeout
        server = SvelteLanguageServer(config, repo_root, settings)
        server.start()
    else:
        raise

Prevention

Set a generous server-ready timeout for cold starts and CI machines.
Pre-warm npm caches (install typescript/svelte LS once) before starting.
Confirm the workspace has typescript installed for the companion tsserver.

When it happens

Trigger: Starting the Svelte language server when the workspace/configuration handshake and readiness signal from the Svelte or companion TypeScript server never arrive within the timeout — slow cold starts, huge workspaces, or the server process hanging/crashing before ready.

Common situations: First run on cold npm caches downloading packages, very large monorepos, slow CI machines, or broken node/tsserver installs leaving the companion server stuck.

Understand the failure class

Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/66594c91a506b647. Report an issue: GitHub.

Appendix: source

Thrown at src/solidlsp/language_servers/svelte_language_server.py:156

                    "languages": ["svelte"],
                }
            ],
            "tsserver": {"path": self._custom_tsdk_path},
        }
        return params

    @override
    def _start_server(self) -> None:
        def workspace_configuration_handler(params: dict) -> list:
            items = params.get("items", [])
            return [{} for _ in items]

        self.server.on_request("workspace/configuration", workspace_configuration_handler)
        super()._start_server()

    @override
    def _handle_server_ready_timeout(self, timeout: float) -> None:
        raise TimeoutError(f"Svelte companion TypeScript server did not become ready within {timeout:.0f}s")

    @override
    def _handle_project_indexing_timeout(self, timeout: float) -> None:
        raise TimeoutError(
            f"Svelte companion TypeScript server project indexing did not complete within {timeout:.0f}s ({self.describe_indexing_state()})"
        )


class SvelteLanguageServer(SolidLanguageServer):
    """
    Svelte language server using ``svelte-language-server``.

    ``ls_specific_settings["svelte"]`` keys:
        * ``svelte_language_server_version``: version of ``svelte-language-server``
          to install (default: ``0.18.0``).
        * ``npm_registry``: optional alternative npm-compatible registry URL.
        * ``indexing_timeout``: optional timeout in seconds for companion TS indexing of
          Svelte files. Falls back to ``ls_specific_settings["typescript"].indexing_timeout``

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