On some occasions after system/rutorrent updates etc some browsers fail to load new cache which can result in errors or similar like the following.
JS error: [https://seedboxsolutions.com/rutorrent/# line 2 > injectedScript : 2361] TypeError: can't access property "replace", theUILang.diskUsage is undefined
To resolve this you simply need to clear cache and reload page. Use your browsers in built option or close browser and clear cache with an app like CCleaner.