writeJsonResponse(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);
        }
    }

    protected String detailedMessage(final Throwable t) {
        if (t == null) {
            return "Unknown";
        }
        Throwable target = t;
        if (target.getCause() == null) {
            return target.getClass().getSimpleName() + "[" + target.getMessage() + "]";
        }

                        indexName = configIndex.replaceFirst(Pattern.quote(CONFIG_INDEX_PREFIX), name);
                    } else {
                        throw new FessSystemException("Unknown config index: " + configIndex);
                    }
                    final boolean exists = existsIndex(indexName);
                    if (!exists) {
                        createIndex(configIndex, indexName);