Random NS_ERROR_NET_PARTIAL_TRANSFER in Mozilla Firefox #21569

Describe the bug

When using Mozilla Firefox in my local Angular project I have a random network issue while loading the JS chunks: NS_ERROR_NET_PARTIAL_TRANSFER
It's working fine in Chrome or any other browsers.

The issue was introduced after upgrading my Angular project from v20 to v21. I confirmed the ViteJS lib was changed from 7.1.5 to 7.2.2. And also confirmed the issue is not reproducible when downgrading to Angular v20/Vite 7.1.5.

Vite version where the issue is not reproducible:
└─┬ @angular/build@20.3.3
├─┬ @vitejs/plugin-basic-ssl@2.1.0
│ └── vite@7.1.5 deduped
└── vite@7.1.5

Vite version with reproducible issue:
└─┬ @angular/build@21.0.5
├─┬ @vitejs/plugin-basic-ssl@2.1.0
│ └── vite@7.2.2 deduped
└── vite@7.2.2

• Note: I cannot add a reproducible scenario because it only fails on 'big' projects with many chunk.js resources.

Reproduction

n/a

Steps to reproduce

• Use Mozilla Firefox in a Angular project v20 (with Vite 7.1.5)
• Upgrade Angular using ng upgrade so we go to the latest, and internally it will upgrade Vite to 7.2.x
• Use Firefox and reload the page (hard reload with Shift + reload) Do it several times and you'll see in the 'Network' tab some of the requests are failing with error NS_ERROR_NET_PARTIAL_TRANSFER

• Environment: Angular CLI dev-server (@angular/build:dev-server) with SSL certificates enabled (HTTP/2)

System Info

System:
    OS: macOS 26.2
    CPU: (8) arm64 Apple M1 Pro
    Memory: 286.56 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.0.0 - /Users/name/.nvm/versions/node/v24.0.0/bin/node
    npm: 11.3.0 - /Users/name/.nvm/versions/node/v24.0.0/bin/npm
    pnpm: 9.12.1 - /opt/homebrew/bin/pnpm
  Browsers:
    Chrome: 144.0.7559.110
    Edge: 144.0.3719.104
    Safari: 26.2

Used Package Manager

npm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.