Old Dec 24, 14, 1:45 am
Join Date: Jan 2009
Location: LHR (sometimes CLE, SFO, BOS, LAX, SEA)
Programs: UA 1K
Posts: 5,812
This usually means that at the very last step where United tried to hold then ticket the inventory for your flight, it wasn't actually available.

By any chance did you include a segment on ANA (NH)? That carrier is notorious for having a bad inventory connection to united.com where UA often sees un-bookable cheap flights.

It seems like United's Web site uses a "safe" approach for inventory: when you go to buy a flight, as it shows you various options and prices, it's showing you currently available flights, but only *when you click purchase* does it reserve the inventory and queue it for ticketing.

This is safer than, say, the AA strategy where doing a "dummy search" actually takes seats out of inventory — see some discussion at e.g. http://roadwarriorette.boardingarea....seat-blocking/ where a person who repeatedly checked whether a business-class seat was for sale managed to cause AA to temporarily sell out the flight!!

The pro of the UA approach is you can close your browser and come back and the seat won't be gone (unless someone else bought it).

But the big downside is that if the inventory is out of date (either for UA flights, someone else buys it; or for non-UA flights, the connection with another carrier is poor and they get bad availability data), you'll see this error page. UA will think they can sell you the seat, but once you hit "pay" you will have a bad time as they try to grab the space and their reservations system says "can't grab, it's not available".

Try your booking one more time. Also give it a shot on third-party booking sites like Expedia or Orbitz, where they may do a better job of honoring their quoted prices or showing more up-to-date inventory.

If you really need to use united.com here, and you can't narrow down the problem to a specific "bad inventory" flight (often a single NH sector that doesn't have quite the right fare class), you can call a United reservations agent, or United.com Web support, in order to complete this purchase. They'll help you find options that are really available and help complete ticketing, and if you weren't already a UA elite who gets waived phone booking fees, they would be likely waive the phone booking fee if you give a convincing explanation that the Web sales channel was giving an error.
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