What about restarting the OMS?
It's basically (with the appropriate environment):
emctl stop oms -all -force
emctl start oms
OS Error 115 means Operation is in progress which is seen here in your provided error:
'CONNECTION_REFUSED [os error=115, ....
So i also think that restarting OMS with emctl stop oms -all -force as Markus Flechtner said may solve the issue.
Webtier is the one responsible to complete the console requests.
May I know what is the status of webtier when you check "emctl status oms" during this time?
What are the recent changes done to the server or EM Configuration before this issue is started?
The issue started after applying the Patch (version 188.8.131.52.17) .
I ran the following commands on the server to fix it:
$OMS_HOME/bin/emctl stop oms -all -force
$OMS_HOME/bin/emctl start oms