We couldn't make changes to our assistant as it shows "Voice Circuits Overloaded" error. Error: TypeError Message: Cannot read properties of undefined (reading 'models') Timestamp: 2025-08-03T04:14:55.057Z Organization ID: feca8c07-4aae-4b21-93ee-120689e1ab23 Assistant ID: e49b7120-ec7a-4764-842e-be2f48837dba We've been facing the same issue for over a week now. All assistants are showing the same error. https://cdn.discordapp.com/attachments/1401419064940695573/1401419065251070002/Screenshot_2025-08-03_121801.png?ex=68918636&is=689034b6&hm=55b12558ec55fc79f0f8b68129ffaa0f846ded95c30c37cecab8e4afde042f4d&

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Hey man, did you manage to fix it? i have the same issue

nahh wasn't able too. Tried to reach out multiple times but the support seems to be non existent

damn, i cant fix the issue i have also

This happens when i create the new agent with custom voice

{
  "name": "New Assistant",
  "voice": {
    "provider": "custom-voice",
    "server": {
      "url": "https://dfdfsdfca/webhook-test/tts",
      "timeoutSeconds": 15
    }
  },
  "model": {
    "model": "gpt-4o",
    "messages": [
      {
        "role": "system",
        "content": "This is a blank template with minimal defaults, you can change the model, temperature, and messages."
      }
    ],
    "provider": "openai"
  },
  "firstMessage": "Hello.",
  "voicemailMessage": "Please call back when you're available.",
  "endCallMessage": "Goodbye.",
  "transcriber": {
    "model": "nova-2",
    "language": "en",
    "provider": "deepgram"
  }
}

I fixed it

Glad the issue was resolved. Please reach out to us if you have any other questions regarding this issue

Thanks @rob but that is for default providers. but what about custom TTS provider it still breaks

Hmm ig that’s a ui issue for custom tts providers. Mine broke because i was using PlayHt and I saw post from Vapi that they’ve removed it from the list hence breaking the assistant. I suppose Create Call still works? Just update the voice to a default one when u need to make changes.

If you are using a custom TTS provider you will need to continue to update the assistant configuration by API. This can be applied to anyone facing issues with not being able to access the assistant page on the dashboard

Ok does it mean assistant keeps working its just now available on UI. But well in this case we loose the ability to test it from dashboard.

Yes, that is correct. The assistant will remain operational when used by API and called by a phone number if it is attached to one currently. Another way to test it is by saving the demo link and keeping it stored somewhere where you can access later such as your web browser bookmarks, then you could test it without needing to access the dashboard. With this method though, you will need to return your voice settings to the default first, then copy the demo link. After saving the demo link, you can then change it back to your custom settings. Just an idea. Let us know if you have any other questions