{"record":{"id":"278719aba3bc0ab2","repo":"BerriAI/litellm","slug":"most-recent-exception-str-all-fallback-attempts","errorCode":null,"errorMessage":"{most_recent_exception_str}. All fallback attempts failed. Enable verbose logging with `litellm.set_verbose=True` for details.","messagePattern":"(.+?)\\. All fallback attempts failed\\. Enable verbose logging with `litellm\\.set_verbose=True` for details\\.","errorType":"exception","errorClass":"Exception","httpStatus":null,"severity":"error","filePath":"litellm/litellm_core_utils/fallback_utils.py","lineNumber":79,"sourceCode":"\n            response = await litellm.acompletion(\n                **completion_kwargs,\n                model=model,\n                litellm_logging_obj=litellm_logging_obj,\n            )\n\n            if response is not None:\n                return add_fallback_headers_to_response(\n                    response=response,\n                    attempted_fallbacks=attempted_fallbacks,\n                )\n\n        except Exception as e:\n            verbose_logger.exception(\"Fallback attempt failed for model %s: %s\", model, e)\n            most_recent_exception_str = str(e)\n            continue\n\n    raise Exception(\n        f\"{most_recent_exception_str}. All fallback attempts failed. Enable verbose logging with `litellm.set_verbose=True` for details.\"\n    )\n\n\ndef completion_with_fallbacks(**kwargs):\n    return run_async_function(async_function=async_completion_with_fallbacks, **kwargs)\n","sourceCodeStart":61,"sourceCodeEnd":86,"githubUrl":"https://github.com/BerriAI/litellm/blob/6c2dcb801bf2b75c18f1bb24140e7cf57465cc4d/litellm/litellm_core_utils/fallback_utils.py#L61-L86","documentation":"Raised by litellm's fallback machinery after EVERY fallback attempt (and the primary attempt) raised an exception. The message contains the most recent exception string plus guidance to enable verbose logging; nothing succeeded, so the caller receives a bare Exception, not a typed litellm error.","triggerScenarios":"Using the fallbacks parameter or Router with fallbacks where the primary model and all fallback models fail — e.g. all keys rate-limited, all endpoints unreachable, or an invalid shared parameter (bad max_tokens) failing identically on every model.","commonSituations":"Exhausted API quota across all providers, a shared invalid argument causing universal failure, misconfigured fallback model names, or a region-wide outage.","solutions":["Set litellm.set_verbose = True (or check logs) and rerun to see each individual failure and its cause.","Fix the most_recent_exception_str cause first — often one root issue (quota, invalid param) fails all models.","Verify every model in the fallback chain exists and is correctly configured (keys, api_base).","Add cooldowns/retries so transient failures don't burn through all fallbacks instantly."],"exampleFix":"# before\nlitellm.completion(model='gpt-4o', fallbacks=['gpt-4o-mini'], messages=msgs)\n\n# after\nimport litellm\nlitellm.set_verbose = True\ntry:\n    litellm.completion(model='gpt-4o', fallbacks=['gpt-4o-mini', 'claude-3-5-sonnet'], messages=msgs)\nexcept Exception as e:\n    logger.error('all fallbacks failed, last error: %s', e)\n    raise","handlingStrategy":"fallback","validationCode":"import litellm\n\ndef chain_valid(models: list[str]) -> bool:\n    return bool(models) and all(isinstance(m, str) and '/' in m for m in models)","typeGuard":null,"tryCatchPattern":"try {\n  await litellm.completion({ model, fallbacks: [...], messages });\n} catch (e) {\n  // all fallbacks exhausted — degrade gracefully (queue, cached answer, user error)\n}","preventionTips":["Validate every model in the fallback chain is configured and reachable before relying on it.","Enable verbose logging in non-production to see per-attempt failures.","Fix the shared root cause (quota/invalid params) instead of adding more fallbacks.","Use Router with cooldowns so transient errors don't exhaust the chain instantly."],"tags":["fallbacks","exhausted","router","resilience"],"backgroundTag":null,"analyzedSha":"6c2dcb801bf2b75c18f1bb24140e7cf57465cc4d","analyzedAt":"2026-08-15T07:12:03.035Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}