Header message of length [...] received but the packetSize is only [...]

Problem

The size of the request header exceeds what's configured for the application.

Solution

Edit your tomcat/conf/server.xml configuration file and add a packetSize="65536" attribute to the appropriate connector. For example, change:

<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

to

<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" packetSize="65536" />

If you are proxying with Apache over AJP you will want to also add a ProxyIOBufferSize directive to your VirtualHost that is set to the same value. This ensures both Apache and Tomcat are configured to use the same values. Example:

ProxyIOBufferSize 65536