Fable 5 blocks 'hello' — users report over-refusal on harmless prompts
Anthropic's newest model, Fable 5, is reportedly refusing completely harmless messages, including simple greetings. Users on r/ClaudeAI have shared cases where typing 'hello' triggered a block. For people who rely on Claude daily, this is a real workflow disruption.
Fable 5 is Anthropic's latest Claude model, released in 2026. Shortly after launch, the r/ClaudeAI subreddit filled with reports of the model refusing innocent messages — the most striking example being a plain 'hello' getting blocked with no explanation.
This is called over-refusal: when a model's safety filters are set too broadly and start catching things that pose no actual risk. For solo developers and makers who use Claude as part of their daily toolkit, unexpected blocks mean broken workflows and lost time. Anthropic has not issued an official response or patch yet, and frustration in the community is growing.
Key points
- Fable 5 has been blocking harmless messages like 'hello' with no clear reason
- The likely cause is over-tuned safety filters — a known problem with new AI model releases
- Developers and makers using Claude API or Claude.ai are seeing unexpected interruptions
- No official fix or statement from Anthropic has been published yet
- The r/ClaudeAI community is actively documenting cases as reports pile up
Quick term guide
- r/ClaudeAI
- r/ClaudeAI is a Reddit community for discussion about Claude.
- subreddit
- A topic-specific community inside Reddit where people post and discuss related content.
- over-refusal
- When an AI declines requests that are actually harmless because its safety rules are set too broadly.
- safety filters
- Built-in rules that stop an AI from producing harmful or dangerous outputs.
- safety filter
- An automatic rule inside an AI model that stops it from producing content it judges as harmful or risky.
- developers
- Developers are people who build software, apps, or websites.
- workflows
- The specific order of steps taken to finish a piece of work.
- AI model
- A program that can understand prompts and produce text, code, or answers.