langgenius/dify · error · NotFound

Conversation Not Exists.

Error message

Conversation Not Exists.

What it means

Raised by CompletionApi.post as a werkzeug NotFound (HTTP 404) when AppGenerateService.generate raises services.errors.conversation.ConversationNotExistsError. For completion (text-generation) apps this is rare because CompletionMessageExplorePayload carries no conversation_id, but the shared generate service can still reference a conversation in edge cases (e.g., a persisted query referencing a stale conversation). The controller translates the service-layer error into a 404.

Source

Thrown at api/controllers/console/explore/completion.py:127

        args["auto_generate_name"] = False

        installed_app.last_used_at = naive_utc_now()
        db.session.commit()

        try:
            response = AppGenerateService.generate(
                session=session,
                app_model=app_model,
                user=current_user,
                args=args,
                invoke_from=InvokeFrom.EXPLORE,
                streaming=streaming,
            )

            # response-contract:ignore compact_generate_response
            return helper.compact_generate_response(response)
        except services.errors.conversation.ConversationNotExistsError:
            raise NotFound("Conversation Not Exists.")
        except services.errors.conversation.ConversationCompletedError:
            raise ConversationCompletedError()
        except services.errors.app_model_config.AppModelConfigBrokenError:
            logger.exception("App model config broken.")
            raise AppUnavailableError()
        except ProviderTokenNotInitError as ex:
            raise ProviderNotInitializeError(ex.description)
        except QuotaExceededError:
            raise ProviderQuotaExceededError()
        except ModelCurrentlyNotSupportError:
            raise ProviderModelCurrentlyNotSupportError()
        except InvokeError as e:
            raise CompletionRequestError(e.description)
        except ValueError as e:
            raise e
        except Exception:
            logger.exception("internal server error.")
            raise InternalServerError()

View on GitHub (pinned to ef8544b173)

Solutions

1. Omit any conversation_id from the request payload for completion apps — completion apps are single-turn.
2. Start a fresh completion request without carrying over state from a chat session.
3. If the app config embeds a conversation reference, re-publish the app in Studio.
4. Verify the installed app is genuinely a completion app and not a mislabeled chat app.

Example fix

// before: forwarding chat state into a completion call
const payload = { inputs, query, conversation_id: lastConversationId }
await post('/completion-messages', payload)

// after: completion apps are stateless — drop the conversation id
const payload = { inputs, query }
await post('/completion-messages', payload)

// Completion apps are single-turn: strip any conversation_id before posting.
function buildCompletionPayload({ inputs, query, files }) {
  // intentionally omit conversation_id
  return { inputs, query, files };
}

function isStatelessCompletionPayload(payload) {
  return !('conversation_id' in payload) || payload.conversation_id == null;
}

try {
  await postCompletion(id, payload);
} catch (err) {
  if (err.status === 404 && /conversation not exists/i.test(err.message)) {
    // drop any conversation reference and retry once
    const { conversation_id, ...rest } = payload;
    await postCompletion(id, rest);
  } else { throw err; }
}

When it happens

Trigger: POST /console/installed-apps/<id>/completion-messages where the underlying generation service resolves a conversation_id (passed via args or referenced in app config) that does not exist for this app/user. Also reachable if a completion app was misconfigured to reference a conversation.

Common situations: Client reuses stale args from a previous chat session on a completion app; app config references a deleted conversation; data import/migration left dangling conversation references; a buggy client sends an extra conversation_id field.

Related errors

• conversation_completed
• Conversation Not Exists.
• Conversation not found
• Conversation Not Exists.
• Conversation Not Exists.

AI-assisted analysis of langgenius/dify@ef8544b173 (2026-08-12). Data as JSON: /api/errors/eb8d502173ecd61e. Report an issue: GitHub.