Login denied - already 3/2 users connected sorry, setting LIMIT_PERUSER

Resolving host name 203.111.11.111...
Connecting to (203.111.11.111).
Connected to (mail.testing.com) -> IP: 203.111.11.111 PORT: 21.
Socket connected waiting for login sequence.
220 SurgeFTP 203.111.11.111 (Version 2.3a1)
USER ding
331 Password required for marcus.
PASS (hidden)
530 Login denied - already 3/2 users connected sorry, setting LIMIT_PERUSER.
Cannot login waiting to retry...

The IP has been changed for security reasons. What caused this problem and how do i fix this?

Thanks.

Hi, the server is full.


Hi, the server is full.

Thanks. This caused the unwanted error. How I make sure that this would not happen when i logged it? I hate to log in unsuccessfully.