LINE is an indispensable communication tool in our daily lives, but many encounter “login failed” issues during device upgrades or app reinstalls. The causes range from simple password errors and changes in phone numbers to insufficient transfer settings or even account bans.
This article categorizes LINE login issues into three patterns and provides detailed emergency fixes and account transfer procedures. We also introduce definitive preventive measures to ensure you never lose your contacts or chat history.
Main Causes of LINE Login Failures
1. Credential Issues (Login Information Errors)
- Forgotten Password: You have forgotten your registered password or are entering an outdated one.
- Incorrect Information: Typos in the registered phone number, email address, or password.
- Account Hijacking: An unauthorized third party has changed your password, rendering your login credentials invalid.
2. Account Transfer and Registration Issues
- Insufficient Transfer Settings: You failed to toggle the “Account Transfer” setting to ON on your old device before switching to a new one.
- Phone Number Changes: You changed your phone number but did not update your account information on the old device beforehand.
- Disconnected SNS Linking: You attempted to log in via Facebook or Apple, but the link to those services has been revoked.
3. System and Account Status Issues
- LINE System Outage: LINE’s servers are down, or the authentication system is experiencing a glitch.
- Account Ban: Your account has been permanently suspended by LINE management for violating Terms of Use (e.g., spam or harassment).
- Verification Code Issues: The SMS verification code is not arriving or has expired.
Emergency Response: Step-by-Step Troubleshooting
Step 1: Basic Refresh and Verification
| Action | Purpose & Operation |
| Verify Information | Double-check phone numbers, emails, and passwords for typos and casing. |
| Restart App/Device | Fully close the LINE app and restart your smartphone. |
| Check Connection | Toggle between Wi-Fi and mobile data to ensure a stable connection. |
Step 2: Password Reset and Authentication
- Reset Password: Tap “Forgot password?” on the login screen, enter your email, and follow the reset URL sent to your inbox.
- Resend Code: If the SMS code does not arrive, wait a few minutes and tap “Resend Verification Code.”
Step 3: Device Transfer Recovery
- Initiate Transfer: Tap “Log In” followed by “Transfer Account.”
- If you have your old number: Log in with the old number/password and enter the verification code.
- If you don’t have the old number: Attempt login via “Log in with Facebook” or “Sign in with Apple” if previously linked.
- Restore History: Once logged in, restore your chat history from your backup (iCloud or Google Drive).
Step 4: Handling Bans or Hijacking
- If Banned: If a suspension notice appears, recovery is virtually impossible. You will likely need to create a new account.
- If Hijacked: If you cannot log in or receive unrecognized notifications, immediately report the unauthorized access via the “LINE Contact Form.”
Prevention: How to Safeguard Your Account
- Register Email and Password (MANDATORY): Always set a password and keep your email address updated. This allows you to log in even if you lose access to your phone number.
- Auto-Backup Chat History (MANDATORY): Go to Settings → Chats → Chat history backup and set up automatic backups to iCloud (iPhone) or Google Drive (Android).
- Prepare for Account Transfer: Immediately before changing devices or phone numbers, go to Settings → Account transfer and toggle “Allow account transfer” to ON (usually valid for 36 hours).
By following these steps, you can resolve LINE login issues quickly and protect your vital data.
