langchain-ai/deepagents · error · MarketplaceError

Plugin {plugin_id!r} is not installed

Error message

Plugin {plugin_id!r} is not installed

What it means

_require_installed_plugin checks the plugin id against load_installed_plugins(strict=True) and raises MarketplaceError when it is absent. This is the guard used by set_installed_plugin_enabled so enable/disable only mutates plugins that are actually installed. Strict mode also means a malformed registry file surfaces here rather than being silently ignored.

Source

Thrown at libs/code/deepagents_code/plugins/discovery.py:153

    if record.source_type in {"github", "git", "url"} and resolved.is_relative_to(
        cache_root
    ):
        if resolved.is_dir():
            shutil.rmtree(resolved, ignore_errors=True)
        elif resolved.is_file():
            resolved.unlink(missing_ok=True)
    return removed


def _require_installed_plugin(plugin_id: str) -> None:
    """Raise when `plugin_id` does not identify an installed plugin.

    Raises:
        MarketplaceError: If the plugin is not installed.
    """
    if plugin_id not in load_installed_plugins(strict=True):
        msg = f"Plugin {plugin_id!r} is not installed"
        raise MarketplaceError(msg)


@plugin_mutation_lock()
def set_installed_plugin_enabled(plugin_id: str, *, enabled: bool) -> None:
    """Set the enabled state of an installed plugin.

    Args:
        plugin_id: Plugin id in `{name}@{marketplace}` form.
        enabled: Whether to enable the plugin.
    """
    _require_installed_plugin(plugin_id)
    set_plugin_enabled(plugin_id, enabled)
    if enabled:
        ensure_plugin_data_dir(plugin_id)


@plugin_mutation_lock()
def uninstall_plugin(plugin_id: str) -> None:

View on GitHub (pinned to a1af029e6e)

Solutions

1. List installed plugins and use the exact id (`name@marketplace`).
2. Install the plugin first with `plugin install <id>` before enabling.
3. If the registry file is corrupt, fix/restore its JSON or reinstall affected plugins.
4. If the plugin was renamed, use the new id.

Example fix

// before
set_installed_plugin_enabled("widget", enabled=False)  # MarketplaceError: Plugin 'widget' is not installed
// after
install_plugin("widget@internal")
set_installed_plugin_enabled("widget@internal", enabled=False)

from deepagents_code.plugins.discovery import load_installed_plugins

def ensure_installed(plugin_id: str) -> None:
    if plugin_id not in load_installed_plugins(strict=True):
        raise SystemExit(f"{plugin_id!r} not installed; run 'plugin install {plugin_id}'")

def is_installed(plugin_id: str, installed: list[str]) -> bool:
    return plugin_id in installed

from deepagents_code.plugins.discovery import MarketplaceError, set_installed_plugin_enabled

try:
    set_installed_plugin_enabled("widget@internal", enabled=False)
except MarketplaceError as exc:
    print(f"toggle skipped: {exc}")  # install the plugin first

When it happens

Trigger: Calling set_installed_plugin_enabled(plugin_id, enabled=...) (or the CLI `plugin enable/disable`) with an id not in the installed-plugins registry, or with a registry that fails strict validation so the id cannot be found.

Common situations: Toggling a plugin after uninstalling it; using a plugin name without the `@marketplace` suffix; hand-editing or corrupting the installed-plugins JSON; a stale id after the plugin was renamed.

Related errors

• No MCP OAuth provider matched {server_url!r}

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/b587aac22332de0c. Report an issue: GitHub.