[Bug - Partner Center] Uploading a new extension package (.zip) in Partner Center fails

Describe the bug

Uploading a new extension package (.zip) in Partner Center fails. The UI shows a generic "Something went wrong. Please check your network settings" banner. The browser console shows an HTTP 400 "The specified block list is invalid." response on the PUT ...blob.core.windows.net/...&comp=blocklist request, preceded by several failed Put Block requests to the same blob endpoint.

The connection is a stable, verified 1.1 Gbps. A previous version of the same extension uploaded successfully.

To Reproduce

1. Go to Partner Center > Microsoft Edge program > the extension > Packages
2. Click Update / upload and select the .zip package (~34 MB, 657 files, Manifest V3)
3. Wait for the upload progress to complete
4. See the error: "Something went wrong. Please check your network settings"
5. Open browser DevTools > Network/Console and observe a 400 (The specified block list is invalid.) response on the PUT ...blob.core.windows.net/...&comp=blocklist request, preceded by several failed Put Block requests to the same blob endpoint

Expected behavior

The package upload completes and the new version is accepted for review/certification, as with previous uploads of this extension.

Screenshots

Desktop (please complete the following information):

• OS: macOS 15 (Sequoia)
• Browser: Microsoft Edge (also reproduced in other browsers)
• Version: 148.0.3967.96

Additional context

N/A