You're sitting there, ready to finally hit "purchase" on that flight to Orlando or Vegas. You’ve checked the dates three times. You’ve picked your Rapid Rewards seat. Then, the screen goes white or a red banner drops from the top. Southwest error code 000999999 stares back at you.
It feels personal. It’s not.
Honestly, this specific error is one of the most frustrating things about the Southwest digital interface because it is so incredibly vague. Most error codes in the airline industry—like those used in the Amadeus or Sabre Global Distribution Systems—point to something specific like "Invalid Credit Card" or "Session Timeout." But 000999999 is essentially the Southwest website throwing its hands up in the air and saying, "Something broke, and I’m not quite sure what."
It’s a catch-all. It's the "Check Engine" light of the aviation booking world.
What is Southwest Error Code 000999999 actually telling you?
At its core, this is a communication failure. Specifically, it happens when the front-end user interface (what you see on your phone or laptop) fails to receive a valid response from the back-end server (the giant database where Southwest keeps its actual flight inventory and pricing).
Usually, this happens during the "commit" phase of a transaction. You’ve sent your data, but the handshake didn't finish. It’s common during high-traffic events, like the massive 72-hour sales Southwest runs or when a major storm causes thousands of people to try and rebook at the exact same moment. If the server is overwhelmed, it drops the connection. When your browser asks, "Hey, did that go through?" and gets nothing back, it generates Southwest error code 000999999.
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Sometimes it's just a "dirty" browser cache. Digital "gunk" builds up. Cookies from previous sessions might conflict with the current price fetch. Southwest’s pricing is dynamic; it changes every few seconds. If your browser is trying to buy a fare that technically "expired" five seconds ago because someone else grabbed the last "Wanna Get Away" seat, the system might glitch instead of giving you a "Fare Sold Out" message.
The "Ghost Booking" Risk
Here is where it gets sketchy. You see the error. You assume the flight didn't book. You try again.
Wait.
Before you click that button again, check your email. One of the biggest risks with Southwest error code 000999999 is the "ghost booking." This happens when the payment goes through, the seat is reserved in the database, but the confirmation page fails to load. If you keep clicking, you might end up with four different charges on your Chase Sapphire card and four different confirmation numbers.
I've seen travelers lose their minds over this during holiday rushes. They end up with $1,200 in "pending" charges because they kept fighting the error code. Southwest is generally good about refunding duplicate bookings made within a short window, but it's a headache you don't need.
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Check your credit card app immediately. If you see a pending charge from "Southwest Airlines," stop. Don't touch the website. Call them or wait 15 minutes for the confirmation email to arrive.
Technical Fixes That Actually Work
Forget the standard "restart your computer" advice. That's a waste of time. If you are stuck in a loop with this error, you need to change how the website sees you.
The Incognito Trick
Open a private or incognito window. This forces the site to treat you as a brand-new visitor with no baggage—literally. No old cookies, no cached pricing data. If the error was caused by a conflict in your browser's memory, this fixes it 100% of the time.
Switch to the App (or Vice Versa)
Southwest’s mobile app uses a different API (Application Programming Interface) than the desktop website. If the website is spitting out Southwest error code 000999999 because of a specific web-server glitch, the app might be perfectly fine. Conversely, if your phone is on a shaky 5G connection, switching to a hardwired desktop can stabilize the handshake.
The VPN Factor
Occasionally, certain IP addresses get flagged by Southwest’s fraud prevention systems (like Akamai or Cloudflare). If you're using a VPN, turn it off. The airline wants to know you're a real person in a real location, not a bot scraping fares. If your IP looks "noisy," the server might just drop your request, resulting in that 000999999 code.
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Why This Happens More During Sales
Think about the Southwest 40% off sales. Everyone hits the site at once. The "Wanna Get Away" and "Wanna Get Away Plus" buckets are small. When 5,000 people are trying to grab the last 2 seats on a flight from BWI to MCO, the database locking mechanism gets stressed.
In database management, "locking" prevents two people from buying the same seat. If the system takes too long to decide who got there first, it might time out. That timeout is often masked by—you guessed it—Southwest error code 000999999. It’s not your fault. It’s just the digital version of a crowded room where everyone is shouting at once.
Talking to Customer Service
If you have to call, don't just say "the site is broken." Tell the agent you are seeing "Error 000999999." They have internal logs. If they see a spike in this specific code, they can escalate it to their IT operations center (the NOC).
Also, mention if you were trying to use a LUV Voucher or a Rapid Rewards flight. Sometimes this error is triggered by a specific payment type. Vouchers are notorious for this. If the voucher has even a one-cent discrepancy or if the name doesn't match the ID perfectly, the system can't process it and defaults to the generic error.
Actionable Steps to Resolve the Error
If you are staring at that code right now, follow this exact sequence to get your flight booked without double-paying:
- Wait 60 seconds. Do not refresh immediately. Give the server a moment to breathe.
- Check your bank account. Look for a "Pending" charge from Southwest. If it's there, you're likely booked. Check your email (including Spam) for a confirmation.
- Switch devices. If no charge appears, move from your laptop to the Southwest mobile app.
- Clear your "Hosted App Data." In Chrome, go to Settings > Privacy > Clear Browsing Data > Advanced > and check "Hosted App Data." This is more effective than just clearing history for airline sites.
- Verify your Rapid Rewards number. Log out and try booking as a "Guest." Sometimes a corrupted user profile causes the glitch. You can always add your RR number to the reservation later using the "Manage Trips" tool.
- Hard Refresh. On a PC, hit
Ctrl + F5. On a Mac, holdShiftand click the reload button. This bypasses the cache entirely and grabs a fresh version of the page from Southwest's servers.
Don't let the code win. Usually, it's just a temporary hiccup in the matrix. If you've tried these steps and it still fails, the flight might actually be sold out at that price point, and the system is struggling to update the display. Try picking the next flight time and see if it goes through.