Upgrading Google ADK from 2.7 to 2.13, I also flipped telemetry from ADK's own schema v1 to schema v2, which follows the OpenTelemetry GenAI semantic conventions.

The upgrade itself was uneventful. What was not: every BigQuery query reading our Cloud Trace spans started returning zero rows. No errors, no warnings. WHERE name = 'call_llm' simply stopped matching anything, because that span no longer exists.

Here are the six traps I hit, in the order they cost me time.

The setup: spans read from BigQuery

Some context on the pipeline, because it explains why the breakage was silent.

Agent spans go to Cloud Trace, and we query them from BigQuery with SQL.…