What causes "Agent not found" in danny-avila/LibreChat?

Verify the agent id exists and is accessible to the requesting user.

danny-avila/LibreChat · error · Error

Agent not found

Error message

Agent not found

What it means

Thrown during agents endpoint initialization when the primary agent (endpointOption.agent) resolves to a falsy value. Before model validation, the code asserts the agent exists; a missing/null agent means the endpoint points at an agent that could not be loaded.

Source

Thrown at api/server/services/Endpoints/agents/initialize.js:251

      })
    : Promise.resolve([]);
  const skillCreateAllowedPromise = skillsCapabilityEnabled
    ? getSkillToolDeps().canCreateSkill({ req })
    : Promise.resolve(false);
  const skillStatesPromise = accessibleSkillIdsPromise.then((accessibleSkillIds) =>
    loadSkillStates({
      userId: req.user.id,
      appConfig,
      getUserById: db.getUserById,
      accessibleSkillIds,
    }),
  );
  const primaryAgentPromise = endpointOption.agent;
  const modelsConfigPromise = getModelsConfig(req);
  const validatedPrimaryAgentPromise = Promise.all([primaryAgentPromise, modelsConfigPromise]).then(
    async ([primaryAgent, modelsConfig]) => {
      if (!primaryAgent) {
        throw new Error('Agent not found');
      }

      const validationResult = await validateAgentModel({
        req,
        res,
        modelsConfig,
        logViolation,
        agent: primaryAgent,
      });
      if (!validationResult.isValid) {
        throw new Error(validationResult.error?.message);
      }

      return { primaryAgent, modelsConfig };
    },
  );

  /**

View on GitHub (pinned to 5ff282f900)

Solutions

Verify the agent id exists and is accessible to the requesting user.
Re-select a valid primary agent for the endpoint.
If recently created, retry after the agent is committed/propagated.
Remove dangling agent references from endpoints or conversations.

Defensive patterns

Strategy: validation

Validate before calling

const primaryAgent = await endpointOption.agent;
if (!primaryAgent) {
  return res.status(404).json({ error: 'The configured agent no longer exists' });
}

Type guard

function isAgentResolved(agent) {
  return agent != null && typeof agent === 'object' && Boolean(agent.id);
}

Try / catch

try { await initializeClient(req, res, endpointOption); }
catch (e) { if (/Agent not found/.test(e.message)) return res.status(404).json({ error: 'Agent not found' }); throw e; }

Prevention

Validate the agent id exists before binding it to an endpoint.
Garbage-collect endpoint/conversation references to deleted agents.
Return 404 cleanly at the controller boundary instead of crashing initialization.

When it happens

Trigger: The agent id referenced by the endpoint/endpointOption does not exist, was deleted, or its async load returned null; the agent belongs to another user and was filtered out by the loader.

Common situations: An agent was deleted but still referenced by an endpoint or conversation; a shared/other-user agent id used without access; a freshly created endpoint whose agent lookup fails due to propagation delay.

Related errors

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/1131021b70641d25. Report an issue: GitHub.