AFAIK this error code means that the IaaS service is not available (or registered).
I am able to pull the request template for other BP's except XAAS
I'm running into a similar issue. I've been able to publish a XaaS blueprint before and get the template, but I can't with my latest XaaS blueprint. Were you able to solve this issue?
Even though previous XaaS blueprints worked directly, for this my workaround was to create a blueprint on vRA and add the XaaS blueprint as a component to it. Now you can execute the request/template call for the new blueprint.
Did you find solution? I have similar issue where I am trying to call XAAS blueprint from brokerage using API.
[UTC:2019-07-04 12:38:47,610 Local:2019-07-04 12:38:47,610] vcac: [component="cafe:catalog" priority="ERROR" thread="tomcat-http--131" tenant="vsphere.local" context="l2wB4FPA" parent="" token="l2wB4FPA"] com.vmware.vcac.catalog.service.impl.RequestServiceImpl.getCatalogItemInstanceBasedSchema:2497 - supplyMissingExternalSchemas failed
java.lang.IllegalArgumentException: Service type id was null or empty
at org.springframework.util.Assert.hasText(Assert.java:181) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at com.vmware.vcac.platform.content.provider.AbstractExternalProviderManager.getProviderFactoryForServiceType(AbstractExternalProviderManager.java:28) ~[platform-content-provider-7.4.0-SNAPSHOT.jar:?]