When you get an error after you update and you click back, the prices you typed in previously are there but the items locations have changed if you sorting them by price and if there are more than 1 unpriced items. So say you have 10 unpriced items, and you clicked back, the prices stays the same but the items locations have changed, so best to always do a f5 to refresh the page.
And even tho getting an error after you clicked update, items that you remove are already removed when you click the back button. Page may not refresh when you click back.