You get error “The client is currently locked against logon” when you try to login to a particular client. But for other clients like 000, its working fine.
Root cause: Remote client copy got failed or stopped manually.
Solution:
1) Login to any other available client or client 000 (should be available in any case)
2) Execute transaction SCC3. It will give a pop up that one of the client is locked due to a failed client copy. Do you want to release the lock. Click Yes and the lock will be removed.
3) You can now check the logs why it got cancelled.
In most of the cases, it fails due to an rfc issue while copying data from large tables.
4) If you want to restart the remote client copy, you will need to login to that particular client and execute SCC9 and then it will restart copying the tables from where it got failed.
Note: Client will be locked again till the remote client copy is finished successfully.