The pandemic is haunting the global supply chain and, by extension, shoppers.

Two months out from the peak holiday shopping season, consumers are encountering empty store shelves, rising prices and shipping delays that seem to stretch into oblivion. Container ships are clogging ports, awaiting cargo or unable to get past the gridlock to unload their goods. Some factories have gone dark, lacking raw materials and hands to run machines.

Shoppers are beginning to fret: A third of the more than 5,700 people recently surveyed by Oracle, which provides cloud services for such large retailers as Prada and Office Depot, worry they won’t get everything on their wish lists and will be paying more when they do. Here’s what you need to know to avoid a holiday shopping nightmare.