Sonnet 4.5 Caching failed, Costs Just EXPLODED

[Haoyang_Zhang]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The cost for sonnet 4.5 just exploded with no caching applied, charging at a price of ~$4/MToken per continuous request.

Steps to Reproduce

Use Sonnet 4.5 in agent mode

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.37
VSCode Version: 1.99.3
Commit: 1910e1fc4fa41b809793f6c5477108b775c0a120
Date: 2025-10-06T04:16:03.009Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.5.0

For AI issues: which model did you use?

Sonnet 4.5

Does this stop you from using Cursor

Yes - Cursor is unusable

[deanrie]

Hey, thanks for the report. We’ll investigate it.

[Haoyang_Zhang]

Need to get my credits back, this bug just burnt all my monthly credits

[Linear]

I strongly suggest you to temporarily suspend this model or at least push a clear notification to all users before this bug is fully resolved. I’ve just burnt over $100 today, which won’t have happened had you done that yesterday.

[Gabriel_Lima]

Same here. Yesterday got switched over to the paid plan, and consequently was charged 16 usd for less than two hours of work, which was not that intensive/heavy work at all. The token consumption was crazy.
So I switched to grok-code-fast-1.

[Tatsuya_Sato]

Having the same issue in the team at the moment. I think a refund should be reasonable

[HippoDuck]

I had this issue back on Sonnet 4 a month ago! Blew through $70 in minutes, with one single prompt from me. They basically said I should have been monitoring it closer.

I jumped ship to Claude Code Max because I just couldn’t understand why it cost so much.

[cfreeman]

This is happening to me on my personal account, but not on my work/teams account.

[jklre]

1 hour of use and im at my monthly limit….

[cfreeman]

@deanrie any updates here? This has effectively locked us all out of sonnet 4.5 usage / probably cost us a bunch of our usage

[deanrie]

The team is investigating this.

[magoo]

also here for my refund, just got ripped $600 in a week

[jmactx]

I am presuming this bug would be the cause of these $6 charges then? I should probably tell my colleague I am sorry for telling him he is an idiot for not knowing how to prompt sonnet 4.5 correctly… right?

[jmactx]

I was thinking about doing this before finding this bug post. How has your experience been? Worth the jump? Any idea how much more usage you get?

[Joseph_Manghan]

This is absolutely preposterous. Needs urgent fixing and refunding.

[HippoDuck]

Has anyone had any updates from Cursor? I just get what appears to be AI generated responses from them that they’re looking into it. And nothing else. Seems like something they may try to sweep under the rug and hope people forget about.

[HippoDuck]

It’s been great. Highly recommend Claude Code over Cursor. I don’t think I would go back.

[kinder_grinder]

I am wondering is that way I faced this warning on Sep. 27 https://x.com/kinder_grinder/status/1971813463304626376

[Haoyang_Zhang]

Refund received, thanks team

[HippoDuck]

Still waiting for a refund here. Anyone else?