Confirming this bug as of March 18, 2026. Affects both Gemini 3.1 Pro Preview and Gemini 3 Flash Preview. Crashes on first message with zero MCPs enabled, no project folder open, and a single “.” as input — so this is not a context size or configuration issue.
Claude Sonnet 4.6 works without error in the same environment.
Trajectory IDs for Google engineers:
- 60936f5b-66fb-4ddb-b413-e226c26e9200
- ffd93a08-c4cc-4ce3-95a2-e562e7eb8755
- c1f50dd8-146a-45f1-86c7-396e768cb953
- 2429295f-5943-4807-910f-a07a19fdf483
- 46ab4992-116e-4cd1-b205-663d762aa9ab
- 5248c7c4-cd6a-4902-be79-ee18049f2253
All crash at TrajectoryChatConverter.GetNumTokensSinceLastCheckpoint → checkpoint_hook.go:43. This is a server-side bug in the Cortex/Jetski trajectory conversion layer. No user-side workaround exists. Please escalate.