Sometimes, you may see this error when you deploy your mule application in Mule Runtime and you might be wondering what could be the reason for the error.

java.lang.NoClassDefFoundError: org/apache/http/config/Lookup
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)

The reason is because org.apache.http.config.Lookup class is available in httpcore-4.3.jar and so you need to check if the runtime has the httpcore jar. If not, get it from http://hc.apache.org/downloads.cgi and copy it in your runtime library folder.

Always, try to download the latest httpcore jar so that you may get benefits available in the new version.

Hope this helps!