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Sam Nguyen
8 hours ago

ollama update reset my num_ctx to 8k and I blamed the prompt for an hour

Woke up to qwen2.5:14b-instruct-q4_K_M answering like it had amnesia.

Turns out yesterday's Ollama bump wiped the Modelfile override. Activity Monitor still showed ~18GB resident so I kept yelling at the system prompt. It was just 8k context the whole time.

Anyone pinning PARAMETER num_ctx in a Modelfile that survives upgrades, or do you just re-apply it like a peasant every Monday?

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  • Diego Fernández

    I pin it in a tiny Modelfile and also set it in the OpenAI-compat client (num_ctx / options.num_ctx). Ollama upgrades have burned me twice — once on a meeting-booker agent that started summarizing mid-sentence because the history got truncated.

    Also: Mac Activity Monitor lying about resident memory is a classic. I only trust ollama ps now.

    • Nova

      same. i keep num_ctx in a Modelfile checked into the repo and a mise task that runs ollama create … before any long agent loop.

      activity monitor is useless for this. does anyone actually get ollama to keep custom models across major bumps without a recreate?

  • Priya Raman

    Same trap. I keep a one-liner in the repo: ollama create my-qwen -f Modelfile after every bump, then screenshot ollama show before I trust a long RAG pass.

    The "model loaded = context is fine" vibe is how you ship a UI that forgets half the brief. Cleanup time: about 40 minutes of me redrawing copy the model truncated. Never again without the show command.

    • Riley Cho

      the ollama show screenshot habit is underrated. i burned a saturday (and another $20 on cloud fallback tokens) because the local model was truncating tool args mid-json.

      now it's on the friday ship checklist next to "did the webhook secret leak into the PR again"

  • Owen

    Peasant mode here. I pin PARAMETER num_ctx 32768 in the Modelfile and a shell alias that diffs ollama show my-qwen --modelfile against a checked-in copy after every brew upgrade.

    Yesterday's bump still dropped me to 8k once because I renamed the model tag. ollama ps said loaded; the model just forgot half the tool schema. Blamed Zod for 25 minutes before I ran show.

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