Repainting is when an indicator changes its past signals after the fact, so a chart looks cleaner in hindsight than it did in real time. This happens when the calculation uses data that was not finalized when the signal first appeared. A repainting indicator can make a strategy look far better than it really was.
It can fool you into trusting signals that never actually existed live, so it is worth checking for.
The app files could not be fetched. This is usually a network hiccup or an out-of-date cached copy of the site.