Troubleshooting of Ollama API

Troubleshooting of Ollama API

If you have any questions about the Ollama API, you can post them on the Ollama GitHub Repository.

How to Fix "Unauthorized" Error

Error message:

HTTP Error 401
Response: {"error":"Unauthorized"}

Solution

Verify that your API key is correct by testing it with the following curl command:

curl -s -o /dev/null -w "%{http_code}\n" -X POST https://ollama.com/api/chat -H "Authorization: Bearer REPLACE_WITH_YOUR_API_KEY" -H "Content-Type: application/json" -d '{"model":"gpt-oss:120b","messages":[{"role":"user","content":"hi"}],"stream":false}'

Check the returned status code:

• 200 — the API key is valid
• 401 — the API key is invalid or incorrect

How to fix "json: cannot unmarshal object ..."

Error message:

HTTP Error 400: {"error": "json: cannot unmarshal object into Go struct field ChatRequest.messages of type []api.Message"}

Applicable Model:

• gpt-oss:120b

Solution

Root Cause: Incorrect `messages` format. The API expects an array format, but a single object was being sent.

Incorrect Format in PHP: ❌ This is an object

'messages' => ['role' => 'user', 'content' => $message]

Correct Format in PHP: ✅ This is an array containing an object

'messages' => [['role' => 'user', 'content' => $message]]  

Explanation: The `messages` parameter must be an array of message objects, not a single message object. Each message object should contain `role` and `content` properties. The extra square brackets `[]` wrap the message object into an array, which matches the API's expected format.

This fix resolves the `"cannot unmarshal object into Go struct field ChatRequest.messages"` error.

Related links

• Forum: ollama