Editing Troubleshooting of Ollama API


Troubleshooting of [https://ollama.com/ Ollama] [https://github.com/ollama/ollama/blob/main/docs/api.md API]

{{Raise hand | text = If you have any questions about the Ollama API, you can post them on the [https://github.com/ollama/ollama/issues Ollama GitHub Repository].}}

== How to Fix "Unauthorized" Error ==

'''Error message:'''
<pre>
HTTP Error 401
Response: {"error":"Unauthorized"}
</pre>

'''Solution'''

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

<pre>
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}'
</pre>

Check the returned status code:
* '''200''' — the API key is valid
* '''401''' — the API key is invalid or incorrect

== How to fix "prompt too long; exceeded max context length" when sending files ==

'''Error message:'''
<pre>
HTTP Error 400: {"error":"prompt too long; exceeded max context length by 311181 tokens"}
</pre>

'''Applicable Model:'''

* {{kbd | key=gpt-oss:120b}}

'''Solution'''

Root Cause: The entire file content was concatenated into <code>content</code> as raw text. Ollama's <code>/api/chat</code> has no dedicated "file" field — text/document content must be extracted client-side and embedded directly into the message string, which counts fully against <code>num_ctx</code>.

Incorrect Usage: Whole file dumped straight into content
<pre>
'messages' => [[
    'role' => 'user',
    'content' => file''get''contents($path) . "\n\nPlease summary this document"
]]
</pre>

Correct Usage: Truncate / chunk / summarize before sending, and raise <code>num_ctx</code> to match
<pre>
'messages' => [[
    'role' => 'user',
    'content' => $chunkedText . "\n\nPlease summary this document"
]],
'options' => [
    'num_ctx' => 32768
]
</pre>

'''Explanation:'''
Ollama's chat endpoint only has a native <code>images</code> array (base64-encoded, vision models only). There is no <code>files</code> or <code>document</code> parameter. Any non-image file — PDF, txt, docx, log — must be converted to plain text on the client and inserted into <code>content</code>, so its size is not free; it consumes tokens exactly like typed text.

If the resulting text exceeds the model's context window (<code>num_ctx</code>, default is often small, e.g. 2048–4096), the request fails with <code>"prompt too long"</code>. Fix by combining:

* Explicitly setting a larger <code>num_ctx</code> in <code>options</code> (bounded by what the model/hardware can actually support)
* Chunking the file and sending it in multiple requests
* Pre-summarizing or using RAG-style retrieval so only relevant excerpts are sent, instead of the full file

This fix resolves the <code>"prompt too long; exceeded max context length"</code> error when large files are pasted into chat.

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

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

'''Applicable Model:''' 

* {{kbd | key=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
<pre>
'messages' => ['role' => 'user', 'content' => $message]
</pre>

Correct Format in PHP: ✅ This is an array containing an object
<pre>
'messages' => [['role' => 'user', 'content' => $message]]  
</pre>

'''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: [https://www.reddit.com/r/ollama/ ollama]

[[Category: Tools]] 
[[Category: Ollama]]
[[Category: Revised with LLMs]]
[[Category: Generative AI]]