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Fixes · 6 min read

How to Fix the Aion 2 Device Registration Error and Phone Verification Error

Fix the Aion 2 device registration error (40309:500, 43900:500) and phone verification error: the 7-device limit, OTP, launcher steps and a Steam warning.

Updated ·By the Aion2 Atlas team·How we source data

How do I fix the device registration error in Aion 2?

Start simple. Restart and update the NC PURPLE launcher, and if maintenance just ended, give the servers a few minutes. Next, complete the security verification and approve the new device, then restart the launcher. If that fails, open device management on your NC account. Accounts are limited to 7 registered devices, so remove old PCs you no longer use. Also sync your Windows date and time, turn off any VPN and use a stable connection. A widely shared tip from KR/TW players and Reddit is to set up OTP (an authenticator) before device registration. When given the choice, pick OTP instead of Device Registration. Error codes seen with this problem are 40309:500 and 43900:500. One warning for Steam players: don't switch your NC login method to a phone number. Players report that it can block you from relinking Steam.
  • NC accounts allow up to 7 registered devices
  • Error codes: 40309:500, 43900:500
  • Set up OTP first, then register the device
  • Steam users: don't switch login to phone number

Why the error happens

Aion 2 ties your NC account to the machines you play on. The error appears when the launcher sees a device it doesn't trust yet, or when it can't finish the check. The usual causes:

  • Your PC isn't authorized on your NC account yet.
  • You've hit the 7-device limit (a limit NCSOFT has confirmed, according to ExitLag).
  • A hardware, OS or BIOS change made your PC look like a new device.
  • The launcher's session or login expired, PURPLE is out of date, or everyone is logging in at once after maintenance.

Error codes you may see

CodeWhat it usually points toFirst thing to try
40309:500Verification / device checkFinish the security verification, approve the device, restart PURPLE
43900:500Device registrationRemove old devices if you're at 7, then register again

Step-by-step fix for device registration

  1. Close and restart the PURPLE launcher, and let it update. If you're on Steam, restart Steam too.
  2. Wait out the rush. Right after maintenance, logins pile up. Give it a little while before assuming something is broken.
  3. Complete the security verification when prompted, approve the new device and restart the launcher.
  4. Check your device list in NC account device management. If you're at 7, remove PCs you don't use anymore.
  5. Sync Windows date and time (Settings → Time & language → Sync now). A wrong clock can fail the check.
  6. Turn off VPNs and proxies, and switch to a wired or more stable connection if you can.
  7. Set up OTP before registering. Many KR/TW players and Reddit threads recommend adding an authenticator first, then choosing OTP rather than Device Registration when asked.
  8. Still stuck? Contact NC support with the exact error code and the time it happened.

Fixing the phone number verification error

Phone verification fails for different reasons than device registration. Work through these:

  1. Check the format. Pick the right country code and drop any leading 0 from your number.
  2. Make sure you can receive SMS. Good signal, airplane mode off, and a phone restart if texts are stuck.
  3. Use a real carrier number. VoIP and virtual numbers, and some carriers, get rejected.
  4. Stop spamming “send code”. Requests are rate-limited. Wait, then try again once. At the KR launch the limit reset at midnight KST; global timing isn't documented.
  5. Use the OTP route (authenticator app) if it's offered. It skips SMS entirely.

Steam players: read this first

Reddit users reported in October 2026 that changing the NC login method to a phone number can stop you from linking third-party accounts. In practice that means you may not be able to relink Steam. Keep your current login method unless support tells you otherwise.

Other launch errors people hit

  • “You Don't Have Advanced Access”: you tried to enter an Advance Access server without a Founder's Pack. Pick a launch server instead (see server status).
  • “Servers Are Full”: there's a queue. Wait, or try one of the recommended servers.
  • “Failed to Reset Steam Account”: a Steam linking problem. Don't change your login method while troubleshooting (see the warning above).

Frequently asked questions

What is the device limit for Aion 2?＋

NC accounts can have 7 registered devices. If you're at the limit, remove old devices in NC account device management.

What does error 43900:500 mean?＋

It's linked to device registration. Restart PURPLE, approve the device, and clear old devices if you're at the 7-device limit.

Why can't I register my phone number in Aion 2?＋

Usually a wrong format (country code, leading 0), a VoIP or unsupported number, or too many code requests in a row. Wait, check the format and try once more, or use OTP.

Should I use OTP or device registration?＋

Many players recommend setting up OTP first and choosing it over Device Registration. It avoids most registration loops.

Why can't I connect to the Aion 2 game server?＋

Check whether maintenance is running on our [server status](/server-status/) page, restart the launcher, turn off any VPN and sync your PC clock.

Related

Server status →

Maintenance, resets and server list.

New player FAQ →

Launch, platforms and errors.

Twitch drops →

How to link and claim rewards.