How to Fix Claude Repetition Loops & Stuck Output

When using Claude (either via the web interface or the API), you may encounter a bug where the model gets stuck in an infinite loop. It might repeat the exact same sentence, output the same block of code continuously, or start every response with the identical introductory phrase.

This behavior occurs due to how autoregressive language models generate text. Claude predicts the next word based on all preceding text in the current chat history. If a repetitive pattern is established in the context window, the probability of repeating that pattern increases exponentially with each turn.

Follow these practical steps to break the repetition cycle and restore normal model behavior.

1. Clear the Active Context (Start a New Chat) The fastest way to resolve a repetition loop is to start a completely new conversation thread.

Because Claude's generation is heavily biased by the history of the current chat, once a loop starts, it is extremely difficult to prompt the model out of it within the same thread. Starting a new chat completely clears the short-term memory (context window), forcing the model to generate text from a clean slate.

2. Edit the Prompt That Triggered the Loop If you must preserve the current chat history, do not submit a new message complaining about the repetition. Saying "stop repeating yourself" actually adds more instances of the repeated text to the context, reinforcing the pattern.

Instead, use the Edit button on your previous prompt: 1. Hover over your last sent message and click the pencil icon. 2. Modify your prompt slightly to ask for a different format (e.g., "Provide the answer as a bulleted list instead of paragraphs"). 3. Save and submit.

Editing an earlier message deletes all subsequent messages in that branch, effectively pruning the repetitive outputs from Claude's memory.

3. Inject a Pattern-Breaker Directive If the repetition is subtle (such as Claude starting every response with "Sure, I can help with that!"), you need to explicitly forbid the pattern in your system prompt or user instructions.

Add this constraint to your prompt: > "Do not use conversational filler, introductions, or repeat previous phrases. Begin your answer directly with the requested information."

For API users, you can use the system parameter to enforce this globally across all generation cycles.

4. Adjust API Generation Parameters If you are accessing Claude via the Anthropic API or a developer console and experiencing repetition loops, your generation parameters may be misconfigured.

• Check the Temperature: A temperature setting that is too low (e.g., 0.0 or close to it) makes Claude highly deterministic. While good for factual accuracy, it significantly increases the risk of repetition loops in complex generations. Raise the temperature to 0.5 or 0.7 to introduce natural variation.
• Verify System Prompts: Ensure your system prompts do not contain conflicting instructions that force the model into a logical corner where repetition is the only mathematically viable output.

When to Escalate If Claude continues to repeat text across brand-new chat windows, or if you observe widespread repetition bugs across multiple independent devices, there may be an active model degradation issue on Anthropic's servers. Check the official Anthropic Status page. If services are operational, click the thumbs-down icon on the bugged response in the web UI to submit the generation telemetry to Anthropic's engineering team for review.