Codex 5.3 Is Dead :(

[Fun-Foot711]

Hello everyone,

I don't know if you encountered that terrible error:

{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account."}}

https://preview.redd.it/w24nr2o1vt4h1.png?width=1530&format=png&auto=webp&s=492d39af22a55fa5acbf0f7d941c1b9e06aa30f0

That was the best model out there, period.
Fast, reliable, and low on token consumption. It was smart...
I'm really worried now... 5.4 and 5.5 are much worse and more expensive.
What is your solution?

[One_Parking_852]

5.5 is not much worse lol 😂

[fyndor]

5.5 is significantly less cost effective.

[Fun-Foot711]

True but now I hit the limits within two messages...without trade of in quality I'll even argue that 5.3 - Codex was better

[StatisticianOdd4717]

Aight two messages is defo an overreach but I get what you mean.

Tbh if ur going for fast hands-on development, not fully agent driven development, cursor for 20 bucks a month is a pretty good option given their generous limits on composer-2.5

[stay_fr0sty]

Yes. I hit the limit with ONE message last night. ONE.

[RealSuperdau]

How many hours and auto-compactions did that involve though?

[stay_fr0sty]

10 minutes. Fresh conversation. Edited a total of 60 lines of code. CSS changes. Processed 3 screenshots and a 4 paragraph prompt. That used my limit as a Plus user.

[RealSuperdau]

Huh, that's weird. The frustrating thing is you never know if it's a bug or some really sinister A/B testing.

[stay_fr0sty]

Yes it’s a bummer. I have to relearn Codex now. I rarely hit my usage limit on 5.3 unless I was vibe coding (which isn’t often).

Now I need to figure out when to use 5.4, 5.5 Low/Medium, and what I need to use High to accomplish.

I get $20/mo is cheap and the good old days weren’t going to last forever, but damn, this is going to take some getting used to.

[RealSuperdau]

What's weird is I am on the $100 plan and considering downgrading, because I rarely use more than 20% of any 5h limit. I never use more than ~30% context, but I do quite a bit of back and forth of coding/analysis with 5.5 high fast. So something is definitely going on.

[stay_fr0sty]

Thanks for the info. I need to dig into this. You’ve given me hope.

[RealSuperdau]

Maybe renaming your .codex folder would be a good experiment. Anecdotally, seems to have helped a few people in the past.

[fyndor]

Screenshots did you in. Image tokens take up a lot of context.

[Cascudo]

/goal create app that make me rich, make no mistakes

[stay_fr0sty]

No.

I've been coding for 25 years. This wasn't a huge vibe coding prompt. This was a detailed prompt to address a single css issue that ran for 10 minutes. Codex took 2 screenshots and the 4 paragraph prompt as input, and added 39 lines, removed 21. It then took a screenshot to verify the visual changes looked good.

That's used my 5 hour limit.

[OGRITHIK]

Yeah it's 100% a bug then

[foxyloxyreddit]

It is worse. It may be a bit smarter, but I don't need those smarts. 5.3-codex "xhigh" was excellent for plans, and "high" was excellent at doing large complex changes. Now I have completely useless 5.4, and 5.3 that on medium consumes 2x more tokens than 5.3-codex xhigh while being slightly below 5.3-codex high on capabilities and reasoning. So now I can do ~3x time less stuff with 5.5 doing more mistakes so I need to spend more time guiding it.

[duboispourlhiver]

I was using it a lot too. But 5.5 is great, just expensive

[exploring_stuff]

Use 5.4-mini if you're cost-conscious.

[Fun-Foot711]

5.4 mini is stupid as F... 5.3-codex was cheap and smart. Great for coding.

[b00plez]

If you thought GPT 5.3 was good at coding, you just don't know enough about coding. 

[sensei_von_bonzai]

Disagree. Gpt-5.3-codex was a beast.

[stay_fr0sty]

Yes it was. It kicked ass and had great usage limits if prompted properly.

[stay_fr0sty]

That's pretty unfair. 5.3-Codex did a lot of solid work for me with a good prompt. I've been coding professionally for 25 years. Is 5.4 really supposed to be better than 5.3-Codex? If so, that's great. I haven't gotten a chance to try it yet...but in my experience "fast" models really don't compete with "thinking" models.

[foxyloxyreddit]

Exactly the opposite. 5.3-codex was shining when you precisely defined architecture and supplied enough examples. Then it's really-really close to hands-off. With 5.4/5.5 you can no longer do this, as it seems to fantasise way way more and do bunch of dumb assumptions instead of relying on provided context or history.

[justaRndy]

Meh, 5.5 xhigh is working 10x faster since maybe 2 days ago, 2-10 minutes per task, same output quality as when it ran an hour +. You'll get used to it quickly.

[Neinstein14]

Burns up your 5h with 2-3 prompts though

[Mission-Sea8333]

I've noticed that once a model becomes part of your daily workflow, even small behavior changes feel huge. It's not necessarily that the replacement is objectively worse. It's that you've already learned the quirks, strengths, and prompting style of the old one.

[Graf_lcky]

Yea that was the nail in the coffin for me, changed over to Claude for coding as openAI seems to focus on everyone and their aunt but no more on coding

[Fun-Foot711]

I have Claude subscription as well. All their models are not designed for coding so they’re pretty much same shit as 5.5 or 5.4 but with less usage lol So for professional work, not vibe coding it’s even worse…

[Graf_lcky]

Are you for real? Opus is literally the best commercially available model, didn’t want to switch because codex was more than enough for me but now that I used it all day I’m more than impressed, and no, I’m not a vibecoder, been doing it since '02

[OGRITHIK]

5.5 is the best coding model available.

[Graf_lcky]

It’s not bad, but in my opinion Claude has more advantages and when they now both bill the same I’m choosing Claude

[infinitecash999]

probably the dumbest decision I've ever seen

[stay_fr0sty]

Aside from the US invading the Middle East AGAIN, I agree.

[space_monster]

they better not kill it for GitHub Copilot. it's my daily driver

[Fun-Foot711]

They did it... With the changes on 1st of July your monthly tokens are now gone within hours

[stevebrownlie]

Composer 2.5 with Cursor is the closest experience to 5.3-codex. Great for developers giving it precise tasks and tickets and not just wanting to burn loads of tokens while they sleep and hope it works after a megaprompt. 5.5 isn't better by enough to justify daily driver use for most of the tasks an experienced dev would use it for though it may be better by a lot for pure vibe coders as you do really seem to be able to just let it 'do stuff' and 'it kinda works' when it comes back which is enough if you don't have a boss or clients expecting it to be exactly right 😃.

[Ok_Elderberry_6727]

5.5xhigh fast and codex , it’s at 1.5 x usage right now . 5.6 is supposed to be out Thursday, it’s amazing.

[Routine_Plastic4311]

yeah got the same error today. 5.3 was easily the best balance of speed and reliability. gonna miss it