openai harmony response format
✅Solved
I'm trying to use a model via ollama, hf.co/unsloth/gpt-oss-20b-GGUF:q4_K_M, which uses "harmony response format" - does ollama support this response format?
1. The HTTP 500 / template slice index error (the main blocker)
template: :108:130: executing "" at <index $prop.Type 0>: error calling index: reflect: slice index out of range
This is coming from Ollama's template engine, not OpenClaw. The gpt-oss model uses OpenAI's harmony format, and Ollama's built-in template for this model is likely hitting an edge case when OpenClaw sends tool/function definitions. The $prop.Type 0 suggests it's trying to index into a property type array that's empty or structured differently than the template expects. This is a known pain point with newer model formats in Ollama — the GGUF template may not fully support the tool schema format OpenClaw is sending.
Possible fixes:
Check if there's a newer version of Ollama — template bugs for new models get patched quickly
Try the model test without tools enabled first to confirm it's tool-calling that triggers it
You may need a custom Modelfile with an adjusted template
1. The HTTP 500 / template slice index error (the main blocker)
template: :108:130: executing "" at <index $prop.Type 0>: error calling index: reflect: slice index out of range
This is coming from Ollama's template engine, not OpenClaw. The gpt-oss model uses OpenAI's harmony format, and Ollama's built-in template for this model is likely hitting an edge case when OpenClaw sends tool/function definitions. The $prop.Type 0 suggests it's trying to index into a property type array that's empty or structured differently than the template expects. This is a known pain point with newer model formats in Ollama — the GGUF template may not fully support the tool schema format OpenClaw is sending.
Possible fixes:
Check if there's a newer version of Ollama — template bugs for new models get patched quickly
Try the model test without tools enabled first to confirm it's tool-calling that triggers it
You may need a custom Modelfile with an adjusted template
Solution
Nice — that’s exactly the right guard.
What was happening is some tool parameter schemas don’t have a top-level
If you want to upstream this so nobody else hits it, I’d file an Ollama bug with:
- the exact error (
- the minimal template diff you posted
- the model(s) (
Ollama issues: https://github.com/ollama/ollama/issues
Also: if this fixed your OpenClaw setup, please right-click the solution message → Apps →
Mark Solution so Answer Overflow indexes it for the next person.
What was happening is some tool parameter schemas don’t have a top-level
"type"anyOfoneOf$reflen $prop.Type == 0index $prop.Type 0If you want to upstream this so nobody else hits it, I’d file an Ollama bug with:
- the exact error (
template: :108:130 … index $prop.Type 0 … slice index out of range- the minimal template diff you posted
- the model(s) (
gpt-oss:20bgpt-oss:120bOllama issues: https://github.com/ollama/ollama/issues
Also: if this fixed your OpenClaw setup, please right-click the solution message → Apps →
Mark Solution so Answer Overflow indexes it for the next person.
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