Your team maintains a GitLab CE pipeline that builds a CML topology from a YAML definition, boots the lab via the CML REST API, and then runs pyATS tests against the simulated nodes. The pipeline recently began failing at the 'lab-start' stage with the error: 'node definition iosxe-17.03 not found on controller'. The topology YAML was authored months ago and worked previously. The CML server was upgraded last week by the platform team. What is the MOST likely root cause and appropriate fix?