By the way, these are not real errors.
Some data cannot be rebuild automatically each time u change it (e.g. Static Shadows) coz this would slow down the Editor really badly. That’s why you need to rebuild it manually.
In such cases, if you’re getting one of ... NEEDS TO BE REBUILD messages, don’t panic, it’s perfectly fine. After the editing is done, just try looking for the appropriate option under Build tab and click it.
Hope, this helps 