What causes "Thread ${threadSlug} not found." in Mintplex-Labs/anything-llm?

List threads for the workspace and use a current slug

Thread ${threadSlug} not found.

Error message

Thread ${threadSlug} not found.

What it means

HTTP 404 from POST /api/v1/workspace/:slug/thread/:threadSlug/chat when WorkspaceThread.get({slug:threadSlug, workspace_id}) finds no thread. The thread must belong to the resolved workspace; a thread that exists elsewhere still fails. The abort-shaped body names the missing threadSlug specifically, distinguishing it from the workspace-level 404.

Source

Thrown at server/endpoints/api/workspaceThread/index.js:419

        const workspace = await Workspace.get({ slug: String(slug) });
        if (!workspace) {
          response.status(404).json({
            id: uuidv4(),
            type: "abort",
            textResponse: null,
            sources: [],
            close: true,
            error: `Workspace ${slug} not found.`,
          });
          return;
        }

        const thread = await WorkspaceThread.get({
          slug: String(threadSlug),
          workspace_id: workspace.id,
        });
        if (!thread) {
          response.status(404).json({
            id: uuidv4(),
            type: "abort",
            textResponse: null,
            sources: [],
            close: true,
            error: `Thread ${threadSlug} not found.`,
          });
          return;
        }

        const resolvedMode = mode ?? workspace.chatMode;
        if (
          (!message?.length || !VALID_CHAT_MODE.includes(resolvedMode)) &&
          !reset
        ) {
          response.status(400).json({
            id: uuidv4(),
            type: "abort",

View on GitHub (pinned to 3aec848f28)

Solutions

List threads for the workspace and use a current slug
If missing, create the thread: POST /api/v1/workspace/:slug/thread/new, then chat using the returned slug
On 404, invalidate the cached thread and re-resolve once
Ensure the threadSlug comes from the API response field slug, not name

Example fix

// before
const res = await chat(slug, cachedThreadSlug, message);
// after
let threadSlug = cachedThreadSlug;
if (!(await threadExists(slug, threadSlug)))
  threadSlug = (await createThread(slug, { name: 'recovered' })).slug;
const res = await chat(slug, threadSlug, message);

Defensive patterns

Strategy: fallback

Validate before calling

if (!(await threadExists(slug, threadSlug)))
  threadSlug = (await createThread(slug, { name: 'auto-recovered' })).slug;

Type guard

function isThreadNotFound(d) { return d?.type === 'abort' && /Thread .* not found/.test(d.error ?? ''); }

Try / catch

try { await threadChat(slug, threadSlug, msg); }
catch (e) { if (isThreadNotFound(e.payload)) { threadSlug = await createThread(slug); await threadChat(slug, threadSlug, msg); } else throw e; }

Prevention

Store the thread slug from the create response
Revalidate thread before long-running sessions
Auto-create the thread on 404 when idempotency is acceptable

When it happens

Trigger: Correct workspace, wrong or deleted thread slug; thread name used instead of slug; thread removed by another user/session between listing and chatting.

Common situations: Long-lived clients caching a threadSlug past deletion; concurrent users pruning threads; UI deep-links to removed threads.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of Mintplex-Labs/anything-llm@3aec848f28 (2026-08-18). Data as JSON: /api/errors/8c0290a7e7e1ed52. Report an issue: GitHub.