NEW YORK (CNNMoney.com) -- Just as Apple fans were at their jitteriest about the impending delivery of their iPhone 4s, FedEx's online tracking system crashed Wednesday afternoon.
A FedEx spokeswoman said later in the day that the problem was due to a software update and that the issue "should be fixed very soon."
Customers who pre-ordered the new iPhone 4 were slated to start receiving their devices on Wednesday. That had many iPhone buyers hammering FedEx's site for updates on their phone's journey to their door.
But early adopters, take heart: "Package deliveries are proceeding as normal," FedEx (FDX, Fortune 500) said in a statement on its website. "However tracking updates are temporarily being delayed. Please try back later."
Some superfans wouldn't settle for "later." On the site MacRumors.com, customers were tracking a flight headed out of Hong Kong in hopes that it was the jet carrying their beloved iPhones.
Apple initially said the 600,000 pre-ordered smart phones would start being delivered on Thursday. But by Monday, Internet sites were abuzz with news of shipping notifications informing customers that their devices would arrive a day early.
And some customers even received their iPhones two days early, on Tuesday. One of those lucky pre-orderers was Sam Altman, president of the mobile app developer Loopt.
"The FedEx guy kind of joked with me, saying, 'I think I know what this is,'" Altman said. "I was totally shocked. I wasn't expecting it to come until Thursday."
As far as Altman can tell, his early receipt of the iPhone 4 was merely an accident and wasn't related to his position at Loopt. He said he's read reports from around 20 people who mistakenly received the device on Tuesday.
"I've been excited about this phone for a while, and it really is an incredible thing," Altman said.
Pre-order sales started on June 15, but the process became a nightmare for both AT&T and Apple (AAPL, Fortune 500). Users trying to order the iPhone on Apple's website received an error message saying that the request couldn't be processed. Attempts to preorder from AT&T's website yielded similar error messages.
AT&T (T, Fortune 500), the wireless carrier for the iPhone, suspended its pre-orders the next day, and Apple apologized to customers. Some limited supplies will be available for sale to walk-in customers on Thursday through Apple, Wal-Mart, RadioShack and Best Buy stores.