We received the error below when specifying the businessAccountIdentifier.
<?xml version="1.0" encoding="UTF-8"?>
<soap:Header>
<requestId>00054b5323cb9aa10a620d0e3d0b515c</requestId>
<serviceName>FeedService</serviceName>
<methodName>mutate</methodName>
<operations>1</operations>
<responseTime>510</responseTime>
</ResponseHeader>
</soap:Header>
<soap:Body>
<soap:Fault>
<faultcode>soap:Server</faultcode>
<faultstring>[InternalApiError.UNEXPECTED_INTERNAL_API_ERROR @ com.google.ads.api.services.common.error.InternalApiError.<init>(InternalApiErro]</faultstring>
<detail>
<message>[InternalApiError.UNEXPECTED_INTERNAL_API_ERROR @ com.google.ads.api.services.common.error.InternalApiError.<init>(InternalApiErro]</message>
<ApplicationException.Type>ApiException</ApplicationException.Type>
<fieldPath/>
<trigger/>
<errorString>InternalApiError.UNEXPECTED_INTERNAL_API_ERROR</errorString>
<ApiError.Type>InternalApiError</ApiError.Type>
<reason>UNEXPECTED_INTERNAL_API_ERROR</reason>
</errors>
</ApiExceptionFault>
</detail>
</soap:Fault>
</soap:Body>
</soap:Envelope>
Please let us know if you need the SOAP request. We don't want to include it here because it contains sensitive information.