Unblock the agent in OEM 12 C by performing an agent resync from the console I am using OEM 12 c. Today my EM page was showing that one of the agent in unreachable. So, first of all I tried to see the status of the agent and it showed me the agent is alright. [oracle@NODE4 bin]$ ./emctl status agent Oracle Enterprise Manager Cloud Control 12c Release 2 Copyright (c) 1996, 2012 Oracle Corporation. All rights reserved. --------------------------------------------------------------- Agent Version : 12.1.0.2.0 OMS Version : (unknown) Protocol Version : 12.1.0.1.0 Agent Home : /home/dir/oemcc/agent_inst Agent Binaries : /home/oracle/dir/core/12.1.0.2.0 Agent Process ID : 5159 Parent Process ID : 5044 - - - - --------------------------------------------------------------- Agent is Running and Ready Then I tried to upload the agent and found the following error: [oracle@NODE4bin]$ ./emctl upload agent Oracle Enterprise Manager Cloud Control