Error on Update of Event through a channel

My assessment is you have a custom field where the value is null, custom field isn’t found on the form, or it doesn’t match the available options.  You should look at your assyst log and rest log, they may provide more information.  You can also go directly to rest manually try the update.  Are you mapping a custom field?  There are special requirements for doing that and getting it to work; it’s not dynamic in this service management tool, like others.

Using one of the Events, I figured out this Query will return the definition, which contains the two fields that are required, in this case is “MailBox Name” - now the question is how would this relate to the channel or get to update/add to the event?

https://wvtexasyt0004.oppd.oppd-ds.com:8443/assystREST/v2/events/142/definition 

This is the inside element:

        <configuration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="stringConfigurationProperties">
            <fieldSize>NORMAL</fieldSize>
            <immutable>false</immutable>
            <labelColour>
                <rgb>255</rgb>
            </labelColour>
            <mandatory>true</mandatory>
            <name>
                <attribute>
                    <cacheable>false</cacheable>
                    <id>-1</id>
                    <objectAvailable>true</objectAvailable>
                    <stringValue>MailBox Name</stringValue>
                    <stringValueType>1</stringValueType>
                    <type>1</type>
                </attribute>
                <value>MailBox Name</value>
            </name>
            <unavailable>false</unavailable>
        </configuration>
        <id>55390</id>
        <key>change.main.webCustomPropertyValues.55390</key>
        <propertyDefinitionGroupId>30080</propertyDefinitionGroupId>
        <propertyDefinitionGroupType>2</propertyDefinitionGroupType>
        <propertyIdentifier>webCustomPropertyValues.55390</propertyIdentifier>
        <shortCode>MAILBOX NAME</shortCode>
        <type>STRING</type>