Hello Charles,
Thanks for contacting the Pivotal Support Community!.
I think the issue should go away if you move the pdx declaration above in the configuration, currently the XML parser is way to strict and elements should appear in order.
In summary, the following cache.xml should work:
<?xml version="1.0" encoding="UTF-8"?>
<cache
xmlns="http://geode.apache.org/schema/cache"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://geode.apache.org/schema/cache http://geode.apache.org/schema/cache/cache-1.0.xsd"
version="1.0">
<cache-server port="40404" max-connections="20"/>
<pdx read-serialized="true">
<pdx-serializer>
<class-name>org.apache.geode.pdx.ReflectionBasedAutoSerializer</class-name>
</pdx-serializer>
</pdx>
<region name="ROOT">
<region-attributes refid="REPLICATE"/>
</region>
</cache>
Hope this helps.
Cheers.