I know I am replying very late to this thread, but it may help others.
If you just get - "SEVERE: Caught exception (java.lang.NullPointerException) executing org.apache.jk.common.SocketConnection@9cfe1c, terminating thread" it means request is hitting your
tomcat but you need to check your Connector settings in server.xml.
If we dont specify any connector than by default it uses Coyote HTTP/1.1, otherwise we can specify something like - protocol="AJP/1.3".
<Connector port="19080"
maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
enableLookups="false" redirectPort="443" acceptCount="100"
debug="0" connectionTimeout="0"
disableUploadTimeout="true"
protocol="AJP/1.3" />
Today I faced the similar error but removing the protocol="AJP/1.3"
string from server.xml worked fine for me!!!
Hope it help others!!