After 15.6 Upgrade customer was not able to XOG Projects in Production ENV from rest API and getting the below errors.Also please find the full XML file.
ErrorInformation>
<Severity>ERROR</Severity>
<Description>Project Object update failed</Description>
<Exception><![CDATA[CMN-0016: Attribute '<attribute_name>' has an invalid value]]></Exception>
</ErrorInformation>
</Record>
</Records>
</XOGOutput>
</soapenv:Body>
<ErrorInformation>
<Severity>ERROR</Severity>
<Description>Project Object update failed</Description>
<Exception><![CDATA[CMN-0016: Attribute '<attribute_name>' has an invalid value]]></Exception>
</ErrorInformation>
</Record>
Release :
Component : CLARITY PPM SAAS OPERATIONS
The issue may be due to passing "null" as a value in the XOG file, "null" is not a valid value for date field, advised to change integration to instead of sending "null" (how it comes from database) to just empty tag.