langgenius/dify · critical · InternalServerError

Internal Server Error

Error message

Internal Server Error

What it means

Raised by CompletionApi.post as werkzeug InternalServerError (HTTP 500) from the catch-all 'except Exception' block. Any unhandled exception during AppGenerateService.generate that is not one of the specific service/provider/invoke errors triggers this. The controller logs the full traceback ('internal server error.') and returns a generic 500 to avoid leaking internals.

Source

Thrown at api/controllers/console/explore/completion.py:145

            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()


@console_ns.route(
    "/installed-apps/<uuid:installed_app_id>/completion-messages/<string:task_id>/stop",
    endpoint="installed_app_stop_completion",
)
class CompletionStopApi(InstalledAppResource):
    @console_ns.response(200, "Success", console_ns.models[SimpleResultResponse.__name__])
    @with_current_user_id
    @with_session(write=False)
    def post(self, session: Session, current_user_id: str, installed_app: InstalledApp, task_id: str):
        app_model = installed_app.app_with_session(session=session)
        if app_model is None:
            raise AppUnavailableError()
        if app_model.mode != AppMode.COMPLETION:
            raise NotCompletionAppError()

        AppTaskService.stop_task(

View on GitHub (pinned to ef8544b173)

Solutions

1. Check the Dify backend logs for the full traceback logged by logger.exception('internal server error.').
2. Reproduce with the same payload and capture the stack trace to identify the root cause.
3. If intermittent, check DB/Redis/vector-store connectivity and capacity.
4. Report the traceback to the app maintainer or Dify issue tracker if it is a product bug.
5. Retry once; persistent 500s indicate a deterministic bug, not a transient glitch.

Example fix

// before: client treats any 500 as retryable indefinitely
while (!success) { tryCall(); }

// after: log the request id, retry once, then surface to the user
try { tryCall(); }
catch (e) if (e.status === 500) {
  await retryOnce();
  notifyOpsWithRequestId(response.headers['x-request-id']);
}

// A 500 is not reliably preventable client-side; the best pre-flight is to validate the
// payload shape matches CompletionMessageExplorePayload and that required services are up.
function isValidCompletionPayload(p) {
  return p && typeof p.inputs === 'object' && typeof p.query === 'string';
}

function isServerError(err) {
  return err?.status === 500;
}

try {
  await postCompletion(id, payload);
} catch (err) {
  if (err.status === 500) {
    // capture request id, retry once, then surface — do not loop
    captureRequestId(err);
    await retryOnce();
  } else { throw err; }
}

When it happens

Trigger: POST /console/installed-apps/<id>/completion-messages that hits an unexpected exception — a bug in a service, a database error, an unhandled KeyError/AttributeError in the pipeline, a serialization failure, or infrastructure failure (Redis, vector store) not mapped to a specific error.

Common situations: Bug in custom plugin/tool code invoked during generation; DB connection dropped mid-request; vector store or knowledge retrieval threw an unmapped error; version skew between services; out-of-memory or timeout in a worker.

Understand the failure class

• HTTP status errors: handling 4xx and 5xx responses — how to handle 4xx and 5xx responses properly.

Related errors

• Internal Server Error
• app_unavailable
• not_completion_app
• Conversation Not Exists.
• conversation_completed

AI-assisted analysis of langgenius/dify@ef8544b173 (2026-08-12). Data as JSON: /api/errors/478fc740d4b4a816. Report an issue: GitHub.