500 error with:
{"requestError":{"serviceException":

{"messageId":"SVC3002","text":"Error writing output performing %1 on %2 (msg=%3) (ec=%4)","variables":["POST Search","getNamedQueryResponse","Unexpected error reading/updating database:java.lang.NullPointerException","ERR.5.4.5105"]}

}}

Model query (same FitNesse case as above)

400 error with:
<Fault>
<requestError>
<serviceException>
<messageId>SVC3000</messageId>
<text>Invalid input performing %1 on %2 (msg=%3) (ec=%4)</text>
<variables>
<variable>POST Search</variable>
<variable>getModelQueryResponse</variable>
<variable>Required Field not passed.:ModelInvariantId or ModelName or ModelVersionId required if no startNodeFilter data passed.</variable>
<variable>ERR.5.4.6118</variable>
</variables>
</serviceException>
</requestError>
</Fault>

Expecting:
{
"requestError": {
"serviceException":

{ "messageId": "SVC3000", "text": "Invalid input performing %1 on %2 (msg=%3) (ec=%4)", "variables": [ "PUT", "v11/network/l3-networks/l3-network/l3-network-987654321-24-PS2418", "Unknown XML namespace used in payload:blah blah blah blah "ERR.5.6.3011" ] }

}
}