Ollama / Ollama

Ollama gemma4 repetition loop during constrained JSON generation

Fix Ollama gemma4 repetition loop when generating structured JSON with format parameter Includes evidence for Ollama troubleshooting demand.

Source-backed Last updated May 15, 2026 1 source Needs local verification

Category: Ollama
Error signature: Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 15, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Ollama, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect is a Ollama failure pattern reported for developers trying to fix ollama gemma4 repetition loop when generating structured json with format parameter. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Ollama issue #15502: gemma4:31b enters word-repetition loops during constrained JSON generation with free-text string fields. repeat_penalty parameter has no effect at any value (1.0, 1.15, 1.5). Bug rate 60-100% across 39 trials. Three conditions required: gemma4 dense model, format= with JSON schema, free-text string fields. Category mapped to Ollama per approved list.

Common causes

Ollama issue #15502: gemma4:31b enters word-repetition loops during constrained JSON generation with free-text string fields. repeat_penalty parameter has no effect at any value (1.0, 1.15, 1.5). Bug rate 60-100% across 39 trials. Three conditions required: gemma4 dense model, format= with JSON schema, free-text string fields. Category mapped to Ollama per approved list.

Quick fixes

Confirm the exact error signature matches Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect.
Check the Ollama account, local tool state, and provider configuration involved in the failing workflow.
Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect exactly before applying the quick fix.
Compare the failing environment with Ollama versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect mean in Ollama?

Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect indicates the workflow described by "Ollama gemma4 repetition loop during constrained JSON generation" failed in a Ollama context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect?

Check whether this cause matches your environment: Ollama issue #15502: gemma4:31b enters word-repetition loops during constrained JSON generation with free-text string fields. repeat_penalty parameter has no effect at any value (1.0, 1.15, 1.5). Bug rate 60-100% across 39 trials. Three conditions required: gemma4 dense model, format= with JSON schema, free-text string fields. Category mapped to Ollama per approved list.

Is the Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect guidance source-backed?

The "Ollama gemma4 repetition loop during constrained JSON generation" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect?

For "Ollama gemma4 repetition loop during constrained JSON generation", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging Word repetition loop fills num_predict budget, JSON unterminated — repeat_penalty has no effect?

For "Ollama gemma4 repetition loop during constrained JSON generation", collect the failing Ollama command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.