SOAP Object reference not set to an instance of an object - soap

Question

I'm attempting to run a search for a ticket on ChangeGear 5.0. Their API utilizes SOAP requests, and when I run a request to search I get the error "Object reference not set to an instance of an object". I've looked through existing topics concerning the same issue (there are a lot of them), and I've tried all of them with no luck. Non-required parameters are included as empty tags instead of omitted entirely, I've tried capitalizing the names of the parameters, and I've made sure the request is formatted appropriately according to the WSDL.
The provided ChangeGear 5.0 documentation specifies to structure requests like so:
POST /cgweb/cgwebservices/cgwebservices.asmx HTTP/1.1
Host: ...
Content-Type: application/soap+xml; charset=utf-8
<?xml version="1.0" encoding="utf-8"?>
<soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Body>
<Search xmlns="http://www.sunviewsoftware.com/CGWebServices/">
<sessionId>string</sessionId>
<entityType>string</entityType>
<criteria>string</criteria>
<retrieveRelated>boolean</retrieveRelated>
<entityTemplate>string</entityTemplate>
</Search>
</soap12:Body>
</soap12:Envelope>
This is the request I'm POSTing with the specified headers:
<?xml version="1.0" encoding="utf-8"?>
<soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Body>
<Search xmlns="http://www.sunviewsoftware.com/CGWebServices/">
<sessionId></sessionId>
<entityType></entityType>
<criteria></criteria>
<retrieveRelated>true</retrieveRelated>
<entityTemplate></entityTemplate>
</Search>
</soap12:Body>
</soap12:Envelope>
The only parameter I've set is retrieveRelated because as specified by the WSDL it is the only required parameter, but I've also tried setting all the string parameters to arbitrary non-null values and received the same result. I'm sure the API is functional because when I use the login operation it returns successfully:
POST /cgweb/cgwebservices/cgwebservices.asmx HTTP/1.1
Host: ...
Content-Type: application/soap+xml; charset=utf-8
<?xml version="1.0" encoding="utf-8"?>
<soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Body>
<Login xmlns="http://www.sunviewsoftware.com/CGWebServices/">
<userName>...</userName>
<password>...</password>
</Login>
</soap12:Body>
</soap12:Envelope>
Result:
200 OK
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<LoginResponse xmlns="http://www.sunviewsoftware.com/CGWebServices/">
<LoginResult>...</LoginResult>
</LoginResponse>
</soap:Body>
</soap:Envelope>
I am using the same session I used for the login operation. Is there anything else I can try besides including empty tags for omitted parameters or capitalizing their names? The full error is:
500 Internal Server Error
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<soap:Fault>
<soap:Code>
<soap:Value>soap:Receiver</soap:Value>
</soap:Code>
<soap:Reason>
<soap:Text xml:lang="en">Object reference not set to an instance of an object.</soap:Text>
</soap:Reason>
<soap:Node>.../cgweb/cgwebservices/cgwebservices.asmx</soap:Node>
<detail>
<Error xmlns=".../cgweb/cgwebservices/cgwebservices.asmx">
<ErrorNumber>0</ErrorNumber>
<ErrorMessage/>
<ErrorCode>L_REJECT_CHANGES_FAILED</ErrorCode>
</Error>
<Error xmlns=".../cgweb/cgwebservices/cgwebservices.asmx">
<ErrorNumber>0</ErrorNumber>
<ErrorMessage>Object reference not set to an instance of an object.</ErrorMessage>
<ErrorCode>Object reference not set to an instance of an object.</ErrorCode>
</Error>
<Error xmlns=".../cgweb/cgwebservices/cgwebservices.asmx">
<ErrorNumber>0</ErrorNumber>
<ErrorMessage>Object reference not set to an instance of an object.</ErrorMessage>
<ErrorCode/>
</Error>
</detail>
</soap:Fault>
</soap:Body>
</soap:Envelope>

Answer 1

The problem was that the server wasn't adhering to the WSDL. The entityTemplate parameter was required, and without it the server returns the "Object reference not set to an instance of an object" error. When I initially tested the parameters with dummy values, out of coincidence I had accidentally forgot to set this one -- the only one that strayed from the WSDL specification.