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# Python deploy error: exceeded the unzipped maximum size of 250 MB

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Hbmartin (@hbmartin) · 2025-11-01

(To get it out of the way: Yes, I have searched and read the many topics for python function size here.)

I have a small python project/repo with no TS / Next.js / Django. When I run `vercel build` locally it produces a 43 MB `.vercel/output` but when I go to deploy I get the error: `Error: A Serverless Function has exceeded the unzipped maximum size of 250 MB.`

I can't figure out why this error is happening or how to get past it! I’ve tried to hack `du` into the vercel.json `*Command`s to no avail. There is no debugging hooks or settings that I've been able to find otherwise which is quite frustrating. I tried using `outputTracingIncludes` per https://community.vercel.com/t/error-a-serverless-function-has-exceeded-the-unzipped-maximum-size-of-250-mb-https-vercel-link-serverless-function-size/1086/2 but that is Next.js specific

One possibility is that there may be some issues with local vs server module caching e.g. `.uv-cache` but I simply cannot figure out how to investigate that. My local `.venv/lib` is 198MB. (Even then, 43 + 198 = 241 < 250)

When I set `VERCEL_BUILD_SYSTEM_REPORT=1` I get:

```
▲ Build system report
• No memory or disk space problems detected
• Folder sizes on disk:
  ‣ Input source code:     1 MB
  ‣ Build cache:          <1 MB
  ‣ Output files:          6 MB
  ‣ Node modules:        350 MB

```

I find the `Node modules` size very odd given that this is a pure python project/repo. Perhaps the python code is getting bundled into node somehow?

I already have excluded node_modules in my `vercel.json`
```
{
“$schema”: “https://openapi.vercel.sh/vercel.json”,
“functions”: {
“api/**/*": {
“excludeFiles”: "{.pnpm-store,.next,*.cache,node_modules,lib,collections,public,app}/**”
}
}
}
```

I also have an extensive .vercelignore including eg. `**/*.pyc`, `.venv/**` and so on.

Any debugging help would be greatly appreciate, I'd very much like to understand the root cause of the issue here.


Pauline P. Narvas (@pawlean) · 2026-02-25

Update that might help here — Vercel has increased the Python Functions bundle size limit from **250MB to 500MB** (unzipped).

The disconnect between your local `vercel build` output (43MB) and the deployed bundle size can happen because dependencies get resolved differently during the Vercel build process. Either way, with the new higher limit most small Python projects should have plenty of headroom. Worth giving a fresh deploy a try!

Reference: https://vercel.com/changelog/python-vercel-functions-bundle-size-limit-increased-to-500mb