oraios/serena · error · RuntimeError

Failed to download Taplo from {download_url}. Try installing

Error message

Failed to download Taplo from {download_url}. Try installing manually: cargo install taplo-cli --locked

What it means

_download_taplo wraps the whole verified-download-and-extract step in a try/except; if any part fails (network error, 404, corrupt archive, checksum mismatch, extraction failure, missing chmod), it re-raises as RuntimeError with the download URL and the manual-install hint, chaining the original exception. This converts low-level download failures into a single actionable message.

Source

Thrown at src/solidlsp/language_servers/taplo_server.py:206

                archive_type = "zip" if archive_filename.endswith(".zip") else "gz"
                target_path = install_dir if archive_type == "zip" else executable_path
                FileUtils.download_and_extract_archive_verified(
                    download_url,
                    target_path,
                    archive_type,
                    expected_sha256=expected_hash,
                    allowed_hosts=TAPLO_ALLOWED_HOSTS,
                )

                # Make executable on Unix systems
                if os.name != "nt":
                    os.chmod(executable_path, os.stat(executable_path).st_mode | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)

                log.info(f"Taplo installed successfully at: {executable_path}")

            except Exception as e:
                log.error(f"Failed to download Taplo: {e}")
                raise RuntimeError(
                    f"Failed to download Taplo from {download_url}. Try installing manually: cargo install taplo-cli --locked"
                ) from e

    def _create_base_initialize_params(self) -> dict:
        """
        Returns the initialize params for the Taplo Language Server.
        """
        initialize_params = {
            "locale": "en",
            "capabilities": {
                "textDocument": {
                    "synchronization": {"didSave": True, "dynamicRegistration": True},
                    "completion": {"dynamicRegistration": True, "completionItem": {"snippetSupport": True}},
                    "definition": {"dynamicRegistration": True},
                    "references": {"dynamicRegistration": True},
                    "documentSymbol": {
                        "dynamicRegistration": True,
                        "hierarchicalDocumentSymbolSupport": True,

View on GitHub (pinned to 7fcbca7e62)

Solutions

Read the chained exception (raise ... from e) to see the root cause — check network/proxy access to the download_url printed in the message.
Install Taplo manually: `cargo install taplo-cli --locked`, or download the binary from GitHub releases and add it to PATH.
Retry after transient network issues — the install dir is re-created/re-attempted on next server start.
Pin to an existing Taplo version whose release assets still exist, if the failure was a 404 on the pinned archive.

Example fix

// before: failing behind a corporate proxy
ls = SolidLanguageServer.create("taplo")  # RuntimeError: Failed to download Taplo from https://...
// after: pre-install so no download is attempted
export PATH="$HOME/.cargo/bin:$PATH"  # after `cargo install taplo-cli --locked`
ls = SolidLanguageServer.create("taplo")

Defensive patterns

Strategy: try-catch

Validate before calling

import shutil, subprocess
if shutil.which("taplo") is None:
    url_ok = subprocess.run(["curl", "-sfIL", "https://github.com/tamasfe/taplo/releases"], capture_output=True).returncode == 0
    if not url_ok:
        subprocess.run(["cargo", "install", "taplo-cli", "--locked"], check=True)  # pre-install when downloads are blocked

Try / catch

try:
    server = SolidLanguageServer.create("taplo")
except RuntimeError as e:
    if "Failed to download Taplo" in str(e):
        subprocess.run(["cargo", "install", "taplo-cli", "--locked"], check=True)
        server = SolidLanguageServer.create("taplo")
    else:
        raise

Prevention

Pre-install taplo on machines behind restrictive proxies/firewalls.
Configure proxy env vars (HTTPS_PROXY) if the release host requires them.
Verify the pinned Taplo version's release assets still exist before upgrading.

When it happens

Trigger: Auto-install of Taplo runs (binary not on PATH) and FileUtils.download_and_extract_archive_verified raises: unreachable URL, HTTP error, checksum mismatch, unsupported archive format, or extraction into install_dir failing.

Common situations: Corporate proxies/firewalls blocking GitHub release downloads; offline CI runners; transient network failures; Taplo releasing a new version that removes the pinned archive URL (404); insufficient disk space or write permissions in the install dir.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/4f85290408840c8c. Report an issue: GitHub.