If none of the above works, the error is likely (custom game client using outdated D3D9 hooks). In that case, ask the private server admin for a compatibility patch or an official wrapper .
Sometimes "fixing" the error involves rolling back drivers or adjusting how the GPU handles old rendering paths. how to fix d3d9 application error ran online
Modern Windows versions include DirectX 12, but they do not always come with the legacy DirectX 9/10/11 files that games like Ran Online require. If none of the above works, the error