How To Fix Arknights Error Code 400?

Arknights is a popular tower defense game developed by Hypergryph and Yostar. It features unique gameplay mechanics and charming anime-style graphics. However, some users have reported getting an error message with the code “400” when trying to play Arknights. This comprehensive guide will explain what the Arknights error code 400 is, what causes it, and how to fix it so you can get back to enjoying the game.

How To Fix Arknights Error Code 400?

The Arknights error code 400 indicates there was a connection error when trying to connect to the game servers. Some common causes include:

  • Unstable internet connection
  • Server issues on the game’s end
  • Outdated game client
  • Conflicts with antivirus or firewall software

This error prevents you from loading into the game properly. You may get stuck at the loading screen or at the starting menu. The good news is this issue can usually be resolved with some simple troubleshooting.

7 Ways to Fix Arknights Error Code 400

Here are the top methods to fix the Arknights error code 400 and related connection issues:

1. Restart Your Device and Router

A simple device and router restart can often fix temporary network problems causing error 400. Follow these steps:

  • Force close the Arknights app if it’s running in the background
  • Turn off your device
  • Unplug your router and modem for 60 seconds
  • Plug them back in and turn them on to reboot
  • Turn your device back on
  • Retry loading Arknights

Restarting clears out any corrupted temporary data that may be interrupting the connection.

2. Check Your Internet Connection

Make sure there are no issues with your internet causing the error. Try these troubleshooting steps:

  • Run an internet speed test and make sure you have at least 2Mbps download speed for smooth gameplay.
  • If on WiFi, move closer to your router or try switching to a 5GHz band for less interference.
  • Disable any VPN apps that may be slowing your connection.
  • Reset your network settings on your device.
  • Verify your router firmware is updated.
  • Try switching wireless channels on the router to improve connectivity.

A fast, stable internet connection is required to prevent error 400.

3. Update or Reinstall Arknights

An outdated version of the Arknights app can trigger the error. Updating or reinstalling will download the latest files.

On Android:

  • Open the Play Store
  • Search for Arknights
  • If an Update option shows, tap it to update
  • Or select Uninstall then reinstall fresh

On iOS:

  • Go to the App Store
  • Tap your profile picture
  • Select Purchased
  • Search for Arknights and tap Update or Delete then reinstall

This will refresh all game files which may fix error 400.

4. Clear Cache and Data

Corrupted temporary data on your device could be interfering with connectivity. Clearing it out may help.

On Android:

  • Open Settings -> Apps -> Arknights
  • Tap Storage
  • Select Clear Cache and Clear Data
  • Restart device

On iOS:

  • Go to Settings -> General -> iPhone Storage
  • Find Arknights and tap it
  • Tap Offload App to clear temporary files
  • Reinstall Arknights

Wiping the cache and data forces a fresh sync with the game servers which may resolve error 400.

5. Add Arknights to Exclusions

If you have antivirus, firewall or VPN software installed, add Arknights to the exclusion list so it does not interfere with connectivity. Refer to your specific software’s instructions on adding exclusions.

6. Port Forwarding

You can setup port forwarding on your router to allow a stable connection for Arknights. Here are suggested ports to forward:

  • TCP Ports: 1119, 8003
  • UDP Ports: 16000-16018

Refer to your router manual for exact steps on configuring port forwarding. This opens the ports required by the game.

7. Use a VPN

As a last resort, connect to a VPN (Virtual Private Network) before launching Arknights. This masks your IP address and routes your traffic through remote servers that are often more stable for gaming. Some top VPNs to try include NordVPN, ExpressVPN, and TunnelBear.

Connecting to a nearby server through a VPN service may help circumvent any ISP issues triggering error 400.

Contact Customer Support

If you still see Arknights error 400 after trying these troubleshooting methods, you should contact Arknights customer support. Reach out to them on Twitter or Facebook for further assistance. Provide details about when the issue started and what troubleshooting you’ve tried.


Error code 400 in Arknights is generally caused by network connectivity problems. The game requires a stable internet connection to prevent interruptions. Byrestarting devices, updating the game, clearing temporary files, configuring ports, or using a VPN, you can typically resolve this error quickly. If problems persist, contact Arknights customer support. With the right troubleshooting, error 400 can be fixed so you can enjoy uninterrupted Arknights gameplay.


Q: Does error 400 mean I’m banned in Arknights?
A: No, error code 400 is not related to being banned. It is caused by connection issues between your device and Arknights servers.

Q: Should I delete and re-download Arknights to fix error 400?
A: Yes, fully uninstalling then re-downloading the latest version of Arknights can help resolve error 400. This ensures you have fresh game files.

Q: Can using a free VPN help fix Arknights error 400?
A: Yes, a free VPN may help by changing your connection route to Arknights servers which may resolve the error.

Q: Does error 400 only happen on WiFi networks?
A: No, it can also occur on mobile data if you have an unstable cellular connection. Try switching between WiFi and cellular data.

Q: What is the minimum internet speed required to run Arknights smoothly?
A: Arknights requires at least a 2 Mbps download speed for smooth gameplay. Faster speeds are recommended to prevent error 400.

Q: Will changing my DNS settings help fix Arknights error 400?
A: Yes, switching to public DNS servers like Google ( or Cloudflare ( could potentially fix error 400.

Q: Can third-party antivirus apps cause Arknights error 400?
A: Yes, some antivirus apps may block connections resulting in error 400. Try adding Arknights as an exclusion in the antivirus settings.

Q: Is Arknights error 400 a server-side issue?
A: It can be. But error 400 is usually on the user end. Check the official Arknights Twitter for server status updates after maintenance.

Q: How can I contact Arknights customer support about error 400?
A: You can reach them on Twitter @ArknightsEN or Facebook @ArknightsGlobal. Provide details about your issue and troubleshooting.

Q: What if restarting my network devices did not fix Arknights error 400?
A: Try the other troubleshooting steps like reinstalling the game, clearing temporary data, using a VPN, port forwarding, and contacting support.

Q: Will Arknights error 400 prevent me from claiming daily rewards?
A: Unfortunately, yes. Since error 400 prevents accessing the game, you cannot claim daily rewards until it is fixed.


Arknights error code 400 can be frustrating but is fixable using the troubleshooting techniques outlined. The most common solutions are restarting devices, updating the game client, and clearing cached data. Improving your connection speed can also prevent this error from interrupting your Arknights game time. Make sure to reach out for help from customer support if you continue seeing error 400. With the right steps, you can resolve this issue and return to enjoying Arknights.

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