# Auto STT model errors leads to stalled agent **URL:** \ **Category:** Getting Started\ **Tags:** stt, node-js\ **Created:** [April 21, 2026, 7:41pm UTC](https://community.livekit.io/t/auto-stt-model-errors-leads-to-stalled-agent/923 "2026-04-21T19:41:37Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![carlos\_lostao](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/carlos_lostao/32/975_2.png) [@carlos\_lostao](https://community.livekit.io/u/carlos_lostao)\ **Post date:** [April 21, 2026, 7:41pm UTC](https://community.livekit.io/t/auto-stt-model-errors-leads-to-stalled-agent/923/1 "2026-04-21T19:41:37Z")
Over the last week, I’ve noticed a spike in errors during the STT phase when using the ‘auto’ model. Specifically, most of the errors match the one attached below. I wanted to report this and ask for a solution or workaround, as it is affecting roughly one out of every three calls. The typical behavior is that I say something and the agent doesn’t respond; however, after I repeat it a couple of times, it suddenly recovers. ```bash [21:34:10.249] WARN (41350): Failed to parse STT server event rawData: { "type": "final_transcript", "session_id": "09c99ccd-c000-477d-b52b-0bc9f9867e9e", "transcript": "", "start": 34.844, "duration": 7.7, "confidence": 1, "words": null, "language": "es", "extra": null } error: { "type": "ZodError", "message": "[\n {\n \"expected\": \"array\",\n \"code\": \"invalid_type\",\n \"path\": [\n \"words\"\n],\n \"message\": \"Invalid input: expected array, received null\"\n }\n]", "stack": ZodError: [ { "expected": "array", "code": "invalid_type", "path": [ "words" ], "message": "Invalid input: expected array, received null" } ] at new ZodError (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/core.js:39:39) at Module. (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/parse.js:53:20) at inst.safeParseAsync (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/classic/schemas.js:42:57) at recv (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/inference/stt.ts:502:60) at process.processTicksAndRejections (node:internal/process/task_queues:105:5) at async run (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/utils.ts:501:14) "name": "ZodError" } [21:34:10.574] DEBUG (41350): VAD task: END_OF_SPEECH [21:34:10.574] DEBUG (41350): running EOU detection audioTranscript: "" [21:34:10.574] DEBUG (41350): skipping EOU detection [21:34:10.574] DEBUG (41350): overlap speech ended [21:34:20.191] WARN (41350): Failed to parse STT server event rawData: { "type": "final_transcript", "session_id": "09c99ccd-c000-477d-b52b-0bc9f9867e9e", "transcript": "", "start": 42.544000000000004, "duration": 9.95, "confidence": 1, "words": null, "language": "es", "extra": null } error: { "type": "ZodError", "message": "[\n {\n \"expected\": \"array\",\n \"code\": \"invalid_type\",\n \"path\": [\n \"words\"\n],\n \"message\": \"Invalid input: expected array, received null\"\n }\n]", "stack": ZodError: [ { "expected": "array", "code": "invalid_type", "path": [ "words" ], "message": "Invalid input: expected array, received null" } ] at new ZodError (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/core.js:39:39) at Module. (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/parse.js:53:20) at inst.safeParseAsync (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/classic/schemas.js:42:57) at recv (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/inference/stt.ts:502:60) at process.processTicksAndRejections (node:internal/process/task_queues:105:5) at async run (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/utils.ts:501:14) "name": "ZodError" } [21:34:25.574] DEBUG (41350): User away timeout triggered [21:34:26.169] WARN (41350): Failed to parse STT server event rawData: { "type": "final_transcript", "session_id": "09c99ccd-c000-477d-b52b-0bc9f9867e9e", "transcript": "", "start": 52.494, "duration": 5.95, "confidence": 1, "words": null, "language": "es", "extra": null } error: { "type": "ZodError", "message": "[\n {\n \"expected\": \"array\",\n \"code\": \"invalid_type\",\n \"path\": [\n \"words\"\n],\n \"message\": \"Invalid input: expected array, received null\"\n }\n]", "stack": ZodError: [ { "expected": "array", "code": "invalid_type", "path": [ "words" ], "message": "Invalid input: expected array, received null" } ] at new ZodError (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/core.js:39:39) at Module. (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/parse.js:53:20) at inst.safeParseAsync (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/classic/schemas.js:42:57) at recv (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/inference/stt.ts:502:60) at process.processTicksAndRejections (node:internal/process/task_queues:105:5) at async run (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/utils.ts:501:14) "name": "ZodError" } [21:34:27.450] WARN (41350): Failed to parse STT server event rawData: { "type": "final_transcript", "session_id": "09c99ccd-c000-477d-b52b-0bc9f9867e9e", "transcript": "", "start": 58.444, "duration": 1.3, "confidence": 1, "words": null, "language": "es", "extra": null } error: { "type": "ZodError", "message": "[\n {\n \"expected\": \"array\",\n \"code\": \"invalid_type\",\n \"path\": [\n \"words\"\n],\n \"message\": \"Invalid input: expected array, received null\"\n }\n]", "stack": ZodError: [ { "expected": "array", "code": "invalid_type", "path": [ "words" ], "message": "Invalid input: expected array, received null" } ] at new ZodError (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/core.js:39:39) at Module. (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/core/parse.js:53:20) at inst.safeParseAsync (file:///Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/zod@4.3.6/node_modules/zod/v4/classic/schemas.js:42:57) at recv (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/inference/stt.ts:502:60) at process.processTicksAndRejections (node:internal/process/task_queues:105:5) at async run (/Users/carloslostao/Eighteen/realtie/node_modules/.pnpm/@livekit+agents@1.2.0_@livekit+rtc-node@0.13.24_zod@4.3.6/node_modules/@livekit/agents/src/utils.ts:501:14) "name": "ZodError" } ``` ---
**Author:** ![darryncampbell](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/darryncampbell/32/20_2.png) [@darryncampbell](https://community.livekit.io/u/darryncampbell)\ **Post date:** [April 22, 2026, 9:51am UTC](https://community.livekit.io/t/auto-stt-model-errors-leads-to-stalled-agent/923/2 "2026-04-22T09:51:11Z")
Are you just defining `auto` per [https://docs.livekit.io/agents/models/stt/#automatic-model-selection](https://docs.livekit.io/agents/models/stt/#automatic-model-selection) ? As a workaround you can specify the STT provider directly with LiveKit Inference, e.g. Deepgram would be: [Deepgram STT | LiveKit Documentation](https://docs.livekit.io/agents/models/stt/deepgram/#inference) Can you share your STT config so I can reproduce this? ---
**Author:** ![carlos\_lostao](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/carlos_lostao/32/975_2.png) [@carlos\_lostao](https://community.livekit.io/u/carlos_lostao)\ **Post date:** [April 23, 2026, 1:18pm UTC](https://community.livekit.io/t/auto-stt-model-errors-leads-to-stalled-agent/923/3 "2026-04-23T13:18:19Z")
Sorry for the delay: ```javascript stt: new inference.STT({ model: 'auto', language: 'es', modelOptions: { keyterms: KEYTERMS }, }), ``` This is the configuration I have ---
**Author:** ![darryncampbell](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/darryncampbell/32/20_2.png) [@darryncampbell](https://community.livekit.io/u/darryncampbell)\ **Post date:** [April 23, 2026, 2:50pm UTC](https://community.livekit.io/t/auto-stt-model-errors-leads-to-stalled-agent/923/4 "2026-04-23T14:50:57Z")
Thanks for getting back to me. I notice the [docs](https://docs.livekit.io/agents/models/stt/#automatic-model-selection) say to use `stt: "auto:es",` but I still see the same ZodError if I follow the docs exactly, even with the latest Agents JS release, `1.2.8`. **It looks like a bug to me** , can I please ask you to raise an issue in the Agents JS repo at [Issues · livekit/agents-js · GitHub](https://github.com/livekit/agents-js/issues), that way you will receive updates. If you let me know the ID of the issue, I’ll also raise awareness internally. FYI, obviously ZodError is coming from JavaScript, but I did try this setting with a Python agent in case there was some common error or root cause, but this works fine in Python.