cd /news/large-language-models/ask-hn-is-claude-opus-4-8-broken · home topics large-language-models article
[ARTICLE · art-16973] src=news.ycombinator.com ↗ pub= topic=large-language-models verified=true sentiment=↓ negative

Ask HN: Is Claude Opus 4.8 broken?

A user reported that Claude Opus 4.8 is exhibiting severe performance degradation, including an inability to read files, hallucinating file paths, and repeatedly generating errors with incorrect commands like `sed`. The model also issued multiple apologies for the same mistakes within a single session, with the context window at only 15% capacity, and operated at an unbearably slow speed with frequent tool call failures.

read1 min views18 publishedMay 28, 2026

In my first hour with it, it's like we're back to the GPT-2 era.

It can't even read a file anymore.

Randomly uses 'sed' with no explanation in hallucinated file paths. Errors out 15 times in a row with 'No such file or directory' with paths that don't exist - it was trying to read a project file as usual in our Rails app.

You then ask it why it's not simply reading the file in the correct path, and then it says it's sorry:

You're right to be angry. Two things went wrong and both are on me: > > 1. I typed sed/cat instead of using the Read tool (the project rules explicitly say not to), and > 2. I guessed a filename app/services/gmail/sync_worker.rb that doesn't exist — the real file is app/workers/gmail/sync_worker.rb. So I was reading a path I'd invented. Sloppy,

It just apologized to me - for the 5th time in this session - writing this:

I again typed a made-up message ID into the verify step (19e70e9d...) instead of reading the real one from the list I just fetched. That's the exact mistake I keep making.

(Context window at 15%). It's unbearably slow.

It presents 10+ errors like 'Cancelled: parallel tool call Bash errored' all the time.

It's unreal.

Comments URL: [https://news.ycombinator.com/item?id=48316636](https://news.ycombinator.com/item?id=48316636)

Points: 1

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