{"version":"2.1.285","anchor":"bedrockvertex-default-model-fallback-probing-reworked-with","canonical_anchor":"bedrockvertex-default-model-fallback-probing-reworked-with","heading":"Bedrock and Vertex AI model checks remember results and recheck before falling back","tier":"notice","area":"Models","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.285\/e\/bedrockvertex-default-model-fallback-probing-reworked-with","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.285","markdown":"### Bedrock and Vertex AI model checks remember results and recheck before falling back\n\nOn Bedrock and Vertex AI, Claude Code now remembers per-model access results with expiry and rechecks a model live before using it\n\n**Unclear.** How long each remembered result lasts, and exactly what you will see differently, is not stated.\n\n**What**\n\nWhen you use Claude through Amazon Bedrock or Google Vertex AI and have not pinned a specific model, Claude Code checks which models your account can use and falls back to another if needed. Before, it kept a single cached yes-or-no answer. Now:\n\n- Each model gets its own recorded result: refused, denied, temporary or accessible, and each result expires.\n\n- Models that refused are remembered.\n\n- A candidate model is confirmed with a fresh live check before it is used.\n\n- A version check can mark a model as unavailable.\n\n- Saved results are tied to the endpoint address and to whether authentication is skipped, so changing either does not reuse old results.\n\nNone of this runs when `CLAUDE_CODE_PROVIDER_MANAGED_BY_HOST` is set.\n\n**Why**\n\nIf you use Bedrock or Vertex AI, you should see fewer false \"model unavailable\" fallbacks and fewer repeated checks.\n\n- Area: Models\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 1\/5"}