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A postmortem of three recent issues

anthropic.com

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Re: A postmortem of three recent issues

#61
post #8

> Incorrect routing affected less than 0.0004% of requests on Google Cloud's Vertex AI between August 27 and September 16. Matches my experience. I use CC through our enterprise Vertex AI account and never noticed any degradation. In general it seems like these bugs, while serious, were substantially less prevalent than anecdotal online reports would have you believe. We are really talking about a ~1-2 week window he…

i don't trust companies anymore because every time there's a worldwide outage they use softspeak like "we're observing elevated amounts of errors for a small subset of users", hours after some CTO approves to change the status page imho there's a big market gap for companies that are truly honest with customers instead of corporate gaslighting

I'm with you that a market gap for honesty exists - especially on status pages. Making a better product and being honest I'd class as very-very-hard.

I do think an independent service status monitor might be an easier stip-gap and could serve to improve honesty. It's not trivial.

Re: A postmortem of three recent issues

#62

Wow. Sneaky. They do not even state the rate of impact for the XLA bug afaik, which affected everyone, not just claude code users, very vague. Interesting. Claude code made almost half a billion so far[1] (>500m in ARR and its like 9 months old) , and 30% of all users have been impacted at least once, just from the first routing bug. Scary stuff. Their post mortem is basically "evaluations are hard, we relied on vibe…

They likely don't want to say how much of their inference comes from GCP vs. AWS.

Re: A postmortem of three recent issues

#63

With all due respect to the Anthropic team, I think the Claude status page[1] warrants an internal code red for quality. There were 50 incidents in July, 40 incidents in August, and 21 so far in September. I have worked in places where we started approaching half these numbers and they always resulted in a hard pivot to focusing on uptime and quality. Despite this I'm still a paying customer because Claude is a fanta…

What makes it even worse is the status page doesn't capture all smaller incidents. This is the same for all providers. If they actually provided real time graphs of token latency, failed requests, token/s etc I think they'd be pretty horrific.

If you trust this OpenRouter data the uptime record of these APIs is... not good to say the least: https://openrouter.ai/openai/gpt-5/uptime

It's clear to me that every provider is having enormous scale challenges. Claude Code often slows to a crawl and I have to interrupt it and tell it to try again.

This is especially pronounced around 4-6pm UK time (when we have Europe, Eastern US and West Coast US all hammering it).

Even today I was getting 503 errors from Gemini AI studio with model overloaded at that time, nothing on status page.

I really wonder if it would be worth Claude et al offering a cheaper off peak plan, to try and level out demand. Perhaps the optics of that don't look good though.

Edit to add: I think another potential dimension to this is GB200s have been a lot slower to come on stream than probably the industry expected. There's been a lot of defects with various hardware and software components and I suspect the liquid cooling has been difficult to get right (with far more catastrophic failure states!).

Re: A postmortem of three recent issues

#65
post #18

Earlier quoted context omitted.

I don't know about you but my feed is filled with people claiming that they are surely quantizating the model, Anthropic is purposefully degrading things to save money, etc etc. 70% of users were not impacted. 30% had at least one message degraded. One message is basically nothing. I would have appreciated if they had released the full distribution of impact though.

> Anthropic is purposefully degrading things to save money Regardless of whether it’s to save money, it’s purposefully inaccurate: “When Claude generates text, it calculates probabilities for each possible next word, then randomly chooses a sample from this probability distribution.” I think the reason for this is that if you were to always choose the highest probable next word, you may actually always end up with th…

> I think the reason for this is that if you were to always choose the highest probable next word, you may actually always end up with the wrong answer and/or get stuck in a loop.

No, it's just the definition of sampling at non-zero temperature. You can set T=0 to always get the most likely token. Temperature trades of consistency for variety. You can set T to zero in the API, I assume the defaults for Claude code and their chat are nonzero.

Re: A postmortem of three recent issues

#67
post #18

Earlier quoted context omitted.

I'm not sure if you can claim these were "less prevalent than anecdotal online reports". From their article: > Approximately 30% of Claude Code users had at least one message routed to the wrong server type, resulting in degraded responses. > However, some users were affected more severely, as our routing is "sticky". This meant that once a request was served by the incorrect server, subsequent follow-ups were likely…

I don't know about you but my feed is filled with people claiming that they are surely quantizating the model, Anthropic is purposefully degrading things to save money, etc etc. 70% of users were not impacted. 30% had at least one message degraded. One message is basically nothing. I would have appreciated if they had released the full distribution of impact though.

> 30% had at least one message degraded. One message is basically nothing.

They don't give an upper bound though. 30% had at least one message degraded. Some proportion of that 30% (maybe most of them?) had some larger proportion of their messages (maybe most of them?) degraded. That matters, and presumably the reason we're not given those numbers is that they're bad.

Re: A postmortem of three recent issues

#69

The value of figuring out how to make their LLM serving deterministic might help them track this down. There was a recent paper about how the received wisdom that kept assigning it to floating point associativity actually overlooked the real reasons for non-determinism [1]. [1] https://thinkingmachines.ai/blog/defeating-nondeterminism-in...

network traffic and machine load aren't deterministic. I think for the near term, getting full determinism (e.g. for auditing) is going to only be feasible for batch jobs that are not cost sensitive.

A google search isn't deterministic. Neither is loading upvote count on social media.

It's common advice in distributed systems to have a graceful degradation state instead of becoming unavailable. That wouldn't be possible in a system that's completely deterministic.

Re: A postmortem of three recent issues

#70

> On August 25, we deployed a misconfiguration to the Claude API TPU servers that caused an error during token generation. An issue caused by a runtime performance optimization occasionally assigned a high probability to tokens that should rarely be produced given the context, for example producing Thai or Chinese characters in response to English prompts, or producing obvious syntax errors in code. A small subset of…

Simple answer: there are two separate processes here, training and inference.

As you discuss, training happens over a long period of time in a (mostly) hands-off fashion once it starts.

But inference? That’s a separate process which uses the trained model to generate responses, and it’s a runtime process - send a prompt, inference runs, response comes back. That’s a whole separate software stack, and one that is constantly being updated to improve performance.

It’s in the inference process where these issues were produced.

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