Claude Fable users report harmless prompts being blocked
A user on r/ClaudeAI said Claude Fable blocked even a simple greeting or normal prompts as a safety issue. Other commenters said they saw similar blocks with topics like security, biology, and simple analogies. Several users guessed that Custom Instructions, memories, or project files might be triggering the filter.
Key points
- The original user said very short prompts were blocked in Claude Fable.
- Commenters reported similar blocks around security, biology, and analogy prompts.
- Several users pointed to Custom Instructions, memories, or project files as possible causes.
- One commenter said temporary mode worked better for them.
- The thread is based on user reports and guesses, not an official explanation.
Quick term guide
- r/ClaudeAI
- r/ClaudeAI is a Reddit community for discussion about Claude.
- r/claude
- r/claude is a Reddit community for discussion about Claude.
- Claude Fable
- A new Claude AI model released by Anthropic in June 2026
- prompts
- Instructions you give to an AI tool.
- Custom Instructions
- Saved instructions that tell an AI how to respond by default.
- project files
- Files connected to an AI tool so it can use them as context.
- trigger
- A signal or condition that starts a task.
- session
- A continuous period of interaction between a user and a computer program.