The "Client Authentication Failure" error will occur when the game client has detected that your authentication key is no longer valid. To resolve this, follow the steps below.
- Log into your account
- Press the wrench button found on the top right side of your Launcher
- Click on the Recovery button
- Launch the game
- Right click on Black Desert Online in your Steam library and press "Properties"
- Under the "General" tab, press "Set Launch Options"
- In the new window that pops up, write in the following: --licenseRecovery=TRUE
- Click OK
- Upon running Black Desert Online, the Authentication Key recovery window will appear
Also, delete the following in your Black Desert Online installation folder:
- "ads" folder
- Cache Folder
- Delete the content of the following temp folder: C:\Usersusername\AppData\Local\Temp
- Please also delete your Cache Folders in your Documents.
After the above please run a client repair.
Important: Keep in mind that there is a maximum of 3 recovery attempts available.
Thank you for your patience and understanding.