langgenius/dify · critical · InternalServerError

Internal Server Error

Error message

Internal Server Error

What it means

HTTP 500 InternalServerError, raised by the catch-all 'except Exception' in the more-like-this handler after logging 'internal server error.'. Any unhandled exception from generate_more_like_this that is not one of the mapped service errors falls through to this.

Source

Thrown at api/controllers/console/explore/message.py:196

            # response-contract:ignore compact_generate_response
            return helper.compact_generate_response(response)
        except MessageNotExistsError:
            raise NotFound("Message Not Exists.")
        except MoreLikeThisDisabledError:
            raise AppMoreLikeThisDisabledError()
        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>/messages/<uuid:message_id>/suggested-questions",
    endpoint="installed_app_suggested_question",
)
class MessageSuggestedQuestionApi(InstalledAppResource):
    @console_ns.response(200, "Success", console_ns.models[SuggestedQuestionsResponse.__name__])
    @with_current_user
    def get(self, current_user: Account, installed_app: InstalledApp, message_id: UUID):
        app_model = installed_app.app_with_session(session=db.session())
        if app_model is None:
            raise AppUnavailableError()
        app_mode = AppMode.value_of(app_model.mode)
        if app_mode not in {AppMode.CHAT, AppMode.AGENT_CHAT, AppMode.ADVANCED_CHAT}:
            raise NotChatAppError()

        message_id_str = str(message_id)

View on GitHub (pinned to ef8544b173)

Solutions

1. Check the server logs for the traceback logged by logger.exception('internal server error.') — the message identifies the real cause.
2. Retry idempotently once in case the cause was transient (e.g. DB connection).
3. If reproducible, file a bug with the request URL, app_id, and message_id; the controller should be extended to translate the new error type.
4. As a temporary measure, switch the app to a different provider/model to bypass the failing path.

Example fix

// before: no error handling around more-like-this
const r = await get(moreLikeThisUrl(id, mid));

// after: surface 500 distinctly and retry once
try {
  const r = await get(moreLikeThisUrl(id, mid));
} catch (e) {
  if (e.status === 500) {
    await sleep(500);
    const r = await get(moreLikeThisUrl(id, mid)); // one retry
  } else throw e;
}

// No client validation can prevent a true 500; preflight only avoids the mapped 4xx cases
if (!appAvailable(app) || !isCompletionApp(app)) return; // avoids 745/752, not 759

try {
  return await get(moreLikeThisUrl(id, mid));
} catch (e) {
  if (e.status === 500) {
    await sleep(500);
    return await get(moreLikeThisUrl(id, mid)); // single idempotent retry
  }
  throw e;
}

When it happens

Trigger: GET more-like-this triggers an unexpected server-side bug — unmodeled exception in AppGenerateService, a serialization error, DB session fault, or a provider error type not in the explicit except chain. The handler logs the traceback and returns 500.

Common situations: Bug in a downstream service; new error type added by a provider runtime that the controller does not yet translate; resource exhaustion (DB pool); corrupted app config that throws during generation.

Understand the failure class

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

Related errors

• not_completion_app
• app_more_like_this_disabled
• provider_not_initialize
• provider_quota_exceeded
• model_currently_not_support

AI-assisted analysis of langgenius/dify@ef8544b173 (2026-08-12). Data as JSON: /api/errors/35f7fe44acf04f6e. Report an issue: GitHub.