this issue im facing i was building this ai mock interview prep tool by watching the youtube video and im currently stuck with this error in VAPI please help me https://cdn.discordapp.com/attachments/1443616611767418900/1443616612275060837/WhatsApp_Image_2025-11-27_at_19.44.48_0fad3036.jpg?ex=6980127d&is=697ec0fd&hm=54ba644da1e4d04274fa69c323052847d562d72b112c9f34ae77a5f87a210261&

To fix the error: Create a custom credential in your VAPI dashboard, then use the generated UUID as your

credentialId

. Here’s how your tool server config should look (replace the UUID with your actual credential ID):

json
"server": {
  "url": "https://your-api-endpoint.com",
  "credentialId": "550e8400-e29b-41d4-a716-446655440000"
}

Make sure the

credentialId

is copied exactly from your dashboard after creating the credential. For more details, see the [VAPI server authentication docs](https://docs.vapi.ai/server-url/server-authentication). Source: - [Server authentication](https://docs.vapi.ai/server-url/server-authentication)

how to create custom credential in my VAPI dashboard please help me

To create a custom credential in your VAPI dashboard: 1. Go to your VAPI dashboard and navigate to Custom Credentials. 2. Click Create Credential, select Bearer Token (for most cases), enter a name and your API token, then save. 3. Copy the generated

credentialId

(UUID) and use it in your config:

json
"server": {
  "url": "https://your-api-endpoint.com",
  "credentialId": "your-generated-uuid"
}

For more details, see the [VAPI server authentication docs](https://docs.vapi.ai/server-url/server-authentication). Source: - [Server authentication](https://docs.vapi.ai/server-url/server-authentication)

I have a same issue today. Yesterday was working fine, It happens for me when I add a new endcall node or api request or modify the existing one

please help me @etrock

I have an open ticket too. Sadly I'dont know the solution. I created an Assistant and a tool right now

is there any alternative for this?

I use simple assistant not a workflow and created a custom tool to make and api call and added to the assistant

but there are no tools available in the Vapi right?

Same issue here since couple days. When I want to add an API Request node or modify one. Seems a bug since new release

Hi Sam, To resolve the error with the API request node, you need to create and use a custom credential in your Vapi dashboard. Here's how you can create one: 1. Navigate to the Custom Credentials section in your Vapi dashboard. 2. Click on Create Credential. 3. Select the Bearer Token option, enter a name for your credential, and input your API token. 4. Save the credential and note the generated

credentialId

(UUID). Once done, update your tool configuration to include the

credentialId

like this:

json
"server": {
  "url": "https://your-api-endpoint.com",
  "credentialId": "your-generated-uuid"
}

Make sure you copy the

credentialId

exactly from the dashboard. For more details on server authentication, you can check the [VAPI server authentication docs](https://docs.vapi.ai/server-url/server-authentication).

Same issue

i already update your tool configuration to include the credentialId, the error still persists @User help @Vapi Support Bot @Vapi https://cdn.discordapp.com/attachments/1443616611767418900/1455580553322692628/image.png?ex=69553e87&is=6953ed07&hm=4caa747465d22baba5189b37195eb06cb622aeb77462dbeae3e7cd80d2348060& https://cdn.discordapp.com/attachments/1443616611767418900/1455580553989459998/image.png?ex=69553e87&is=6953ed07&hm=03f799dcb42a226caf704720b9d5f749450b2a012cb99bd770ae1b777b285ccb& https://cdn.discordapp.com/attachments/1443616611767418900/1455580554757144770/image.png?ex=69553e87&is=6953ed07&hm=cb4c8dc44b94aad6b7ba9c3229f95af53c46fac48a8463a17794d365d3adef8f&

Since you've already set the

credentialId

to a valid UUID and the error persists, try deleting and re-adding the API Request node or refreshing your browser to clear any UI glitches. If the issue continues, please contact Vapi support directly, as this may be a platform bug not covered in the documentation. For reference, your configuration should look like:

json
"server": {
  "url": "https://your-api-endpoint.com",
  "credentialId": "daaffcdc-f32f-4328-8687-9987bc7b95e0"
}

See the [Vapi server authentication docs](https://docs.vapi.ai/server-url/server-authentication) for more details. Source: - [Server authentication](https://docs.vapi.ai/server-url/server-authentication)

I added just a end call function and I get this error. and "tool": { "type": "endCall", "function": { "name": "untitled_tool", "parameters": { "type": "object", "properties": {}, "required": [] } }, "server": { "url": null, "credentialId": "", "timeoutSeconds": 20 },

Hi Sam, Thanks — based on the logs and recent reports this is the known validation bug where nodes/tools get a blank or empty-string server.credentialId and the platform enforces a UUID. Short checklist and next steps: 1. Quick workarounds (try in this order) • Replace the API Request / EndCall node with a custom Tool (Dashboard: Tools → Create Tool → API Request) and add that tool to your assistant/workflow. Docs: https://docs.vapi.ai/tools/custom-tools • If you must edit the workflow JSON, PATCH the workflow via API to either remove the empty

server.credentialId

field or set it to a valid credential UUID you created. Docs: https://docs.vapi.ai/api-reference/workflow/workflow-controller-update • Refresh the dashboard, clear cache, or open in an incognito window after creating a Custom Credential to ensure the UI shows the new UUID. 2. How to create a Custom Credential (dashboard) • Dashboard → Custom Credentials → Create Credential → choose Bearer Token (or needed type) → name + token → Save → copy the generated UUID and paste into your node/tool server. Docs: https://docs.vapi.ai/server-url/server-authentication 3. If the above fails • Provide your workflow ID and a call/workflow screenshot showing the offending node JSON (or paste the node JSON). We can escalate to engineering to reset your org's tool/server state. Relevant debugging guide: https://docs.vapi.ai/debugging Which would you like to try first — create a custom tool or paste the workflow ID so I can escalate?