Hi! Would you be able to take a screenshot? It will help a lot.

Also, could you try uninstalling and installing the mini client.

There are two versions, I have provided the link below.

Mini Client 2.3 (Older version)

Mini Client 2.4 (Newer version)

For future purposes, I do recommend using the Bug/Support section for any bug/support related inquiries. You can find it here.

Hi! Is that the same error message you get when you use the new mini client provided?

Not to worry! Can you tell me which server you are from and your in-game name? I can ask the team.

I highly recommend contacting Customer Service as they can better troubleshoot for you. You can find it here.

Hi! Thank you, could you also check if something might be blocking the Mini Client? For example, an Antivirus program might be something that could stop the Mini Client from working properly.

Hi! You c*ways put the NarutoOnline.exe as an exception (The exception list in Anti-Virus) so that it does not block the Mini Client from opening. However, disabling Anti-Virus should be a way to get it to work, but not recommended as it is your computer's Anti-Virus program to defend itself.