Oracle.ons.NoServersAvailable: Subscription Time Out || workaround and Patch

                      Recently after  Upgrading Fusion Middleware from 12.2.1.0 to 12.2.1.3, while I try to connect data source with the 12c database. 

I see one issue saying that  Oracle.ons.NoServersAvailable: Subscription Time Out.

After some research, I found that we need to add one parameter in setDomainEnv.cmd or sh.

It turns out this is a bug in the JDBC driver bundled with WebLogic 12.2.1.3.0 and there is a simple workaround for it:

set the parameter -Doracle.jdbc.fanEnabled=false to JAVA_OPTIONS in setDomainEnv.sh file and restart all the servers in the domain

Or for the permanent fix, you can install patch provide by Oracle Patch 26045997

Happy Learning...😊