For Lost Ark error 105, restart the PC and verify the Lost Ark files in Steam before reinstalling anything. Then install Windows updates and follow Lost Ark's Easy Anti-Cheat checks, including a malware scan and checking whether security software quarantined a game file. Do not delete anti-cheat system files or turn antivirus protection off permanently.
Take a screenshot of “105: Corrupted Data Found” and note whether it appears before the menu or while changing areas. This gives support a useful failure point if file repair does not work.
2
Restart Windows and Steam
Close Lost Ark and Steam, then restart the PC. Open Steam only after Windows finishes starting and test the game once before changing files.
3
Verify the Lost Ark files
In Steam Library, right-click Lost Ark and choose Properties > Installed Files > Verify integrity of game files. Let the check and any replacement download finish; Steam notes that a small number of local configuration files may not verify and can usually be ignored.
Open Settings > Windows Update, install available updates, and restart the PC. Lost Ark Support includes current Windows components in its Easy Anti-Cheat checklist.
5
Check Easy Anti-Cheat and security
Follow Lost Ark Support's Easy Anti-Cheat article to repair the service if its error appears. Run a full malware scan and check your antivirus quarantine for Lost Ark or Easy Anti-Cheat files; restore only files the official security tool identifies as safe.
If verification repeatedly replaces files but error 105 returns, uninstall and reinstall Lost Ark through Steam. Keep the screenshot and verification result for Lost Ark Support if a clean install still fails.
Video walkthrough
If it does not work
If the error begins only after a security alert, review the quarantine record before making exclusions; do not assume every blocked file is safe.
If error 105 returns after a clean install, stop repeating reinstalls and send Lost Ark Support the error screenshot, failure point, Windows version, and Steam verification result.
ⓘ Sources and verification
Checked against official documentation on . Scope: Windows PC with Steam.
The current written steps follow the linked company documentation. The preserved video may show older menus.
