"We're sorry. The fare for the flights you selected just sold out. Please search again to view and select alternate flights."

And I know its total BS, because I search for the flight and it keeps coming up with the same price and inventory, but whenever I try to actually purchase the ticket, it goes back to this screen.
I've also found this happens more often if you try selecting the 'upgrade to first class for only xxx'.

I have had the following happen to me twice in 3 months. I reserve a flight on delta.com, and find (after arriving at airport) that all my flights on my domestic itinerary have been flagged with "declined elite upgrade". After hours on the phone with delta, they finally sent an email explaining they do this on purpose. This happens if you 1. don't log in before searching for a flight, 2. come to delta.com through kayak or similar, or 3.book a trip through a saved trip template. This seems incredibly stupid:

Dear Sir,

Thank you for contacting Delta Air Lines.

We are truly sorry for the frustration and inconvenience you experienced
concerning your complimentary Elite upgrade.

We contacted our delta.com team and were able to identify three possible
causes that some elite-level SkyMiles members� Complimentary Medallion
Upgrades are not being automatically requested at the time of booking,
or are being declined in error.

First possible cause, the customer is not logging-in to delta.com prior
to beginning their flight search. If the customer waits to login after
selecting their flights, their upgrades will be declined automatically.
This is one more reason to encourage our elite customers to login
immediately upon accessing delta.com.

Second possible cause, the customer is using a 3rd party travel web
site. Sites such as www.kayak.com allow customers to shop and select
their flights before redirecting the customer to the airline�s web site
to complete their purchase transaction. When Medallion customers do
this, their upgrades are automatically declined during the transition
from the 3rd-party site to delta.com because the flights have already
been selected.

Lastly, the customer is using a saved trip template which specifies �no
upgrade.� Each time the customer uses this �no upgrade� trip template in
the booking path, their upgrade will be declined automatically. To
correct this problem, customers can access the Flights tab of their
online Profile to add/edit/delete their trip templates.

Please understand we require that you are logged in prior to booking
travel for the automatic process to take place. We apologize for any
frustrations this may be causing you.

We hope the above information helps to clarify the booking process in
more detail. Further, we wanted to assure you that Delta is continually
seeking ways to bring about improvements and enhancements to our
services. Your comments being one of our most valued customers will help
us identify and improve the options you value most and will help shape
the changes we develop in the future.

Thank you again for giving us an opportunity to respond to
your concern. We very much appreciate your Platinum Medallion loyalty
to Delta and look forward to the privilege of serving you again soon.

Sincerely,

Alice Holiday
Medallion Desk
www.delta.com

I just call them up and tell them. They book it and will honor the correct price.

Is it just my browser or is delta.com website broken. Can't even see the login option. Menus hanging on right side. Misc. issues. Started for me this morning. Does not work in IE 8 nor Chrome.

Nevermind. I forced both of my browsers to perform a full reload and all is well. It must have had a bug at the moment I loaded the page earlier today. All is well.

This is weird. After running a flight search, the red "select" button for choosing the first segment doesn't work. I've tried Safari for Mac and Firefox for Windows.

March 6, 2012 438p EST:

Internet Explorer & Firefox

Select one-way IND - MSY 03/28/12

805a - 943a IND - ATL DL 1759
1050a - 1135a ATL - MSY DL 1462

Can't hit the select button. In fact now that I'm looking cannot select any of the flights. Weird.

Update: 443p EST

mobile.delta.com seems to work - allows you to select a flight.

Trying to book ABQ-AUS on 4/22-4/25 RT and have a problem. While expert flyer shows inventory available, I get:

Delta does not have any flights scheduled that match your request. Please change your cities or dates, or for further assistance call Delta Reservation Sales at 800-221-1212.

Can't exactly call sales at the moment as I'm in a conference. Anyone else aware of booking issues or an Austin specific issue?

Search engine seems to be hosed... search by price doesn't work, it returns all searches as if I selected by schedule. No price available until I select flights.

Yeaterday: Used ITA App to check prices to Buenos Aires, indicated $1400 and change. Went to Delta web reservation site, used same itinerary as ITA indicated, +$4,000. Called Delta reservations, used ITA itinerary, quoted $2,300 and change. Orbitz had the $1423.00 fare and booked it. Wish I could understand the logic.

Yeah well i don't understand how this works with delta.

Saw flights for the same date quoting 2.400 euro from ATL-ATH in their website and checking it with kayak.com i saw 1.450 euro!

For several days delta.com has been acting glitchy and slow. I have tried both IE 9 and Google Chrome browsers. This is horrible for the ariline. Does anybody know how they allowing this to happen? Who is doing their IT??? I'm now thinkng twice before booking trips online. I really do not want to go back to the (gasp) telephone.

Unable to pull up existing flights. Got the message, "There was a difficulty in retrieving your reservations."

I can fix the seat assignment later, but personally, I believe I'm owed compensation for the cringe-worthy grammar.

Mike

They call it DL.dumb for a reason.

Yes, its gotten worse with the "new and improved" search interface as well.