PATCH requests with streaming body fail with "internal error"

[kozoy]

Environment

• @cloudflare/containers: v0.0.30 (latest)
• Wrangler: 4.49.1
• Node.js: (runtime version)
• Date: 2025-11-21

Description

PATCH requests containing streaming request bodies fail with an "internal error" when
using container.fetch(). The error occurs in the Worker SDK layer before the request
reaches the container.

Use Case

Running a Zot OCI registry container. When pushing images via podman push:

• POST /v2/<name>/blobs/uploads/ (Content-Length: 0) → ✅ 202 success
• PATCH /v2/<name>/blobs/uploads/<uuid> with blob data → ❌ 500 Internal Server
  Error

Error Message

Error: internal error; reference = e5634i0hnfo8psp6kpb2vaqv
at async Object.fetch (index.js:929:22)

Cloudflare Reference ID: e5634i0hnfo8psp6kpb2vaqv

Worker Code

Following the official example pattern from the documentation:

import { Container, getContainer } from "@cloudflare/containers";

export class ZotContainer extends Container {
  defaultPort = 8080;
  sleepAfter = "30m";
  enableInternet = true;

  envVars = {
    AWS_ACCESS_KEY_ID: "...",
    AWS_SECRET_ACCESS_KEY: "..."
  };
}

export default {
  async fetch(request, env) {
    const container = getContainer(env.ZOT, "zot-registry-singleton");
    const response = await container.fetch(request);
    return response;
  },
};

Observations

1. Container logs show PATCH requests never reach the container
   - Container receives and processes POST requests successfully (returns 202)
   - Container never receives PATCH requests - they fail in the Worker layer
2. Error occurs at SDK level
   - Stack trace points to index.js:929:22 in the bundled SDK code
   - Worker outcome is "exception"
   - Execution model: "stateless"
3. Appears specific to streaming bodies
   - POST with empty body (Content-Length: 0): ✅ Works
   - PATCH with streaming data (Content-Length: 3930425, ~4MB): ❌ Fails
   - Tested with different image sizes (2MB - 4MB) - all fail

Request Details

Failing PATCH request:

• Method: PATCH
• Content-Type: application/octet-stream
• Content-Length: 3930425 (3.9 MB)
• Path: /v2/r2-test/alpine/blobs/uploads/

Related Issues

This appears similar to #98, which was marked as resolved in October 2025. However, the
issue persists for PATCH requests with streaming bodies. Possible explanations:

• Different code path for PATCH vs POST
• Regression in recent SDK version
• Issue only affects certain request patterns (streaming body with Content-Length
  header)

Additional Context

• Container image: ghcr.io/project-zot/zot-linux-amd64:v2.1.0
• Durable Object singleton pattern with max_instances = 1
• enableInternet = true configured for R2 S3 API access
• Container starts successfully and processes GET/HEAD/POST requests correctly

Logs

Worker logs (stateless):

  {
    "outcome": "exception",
    "executionModel": "stateless",
    "exception": {
      "message": "internal error; reference = e5634i0hnfo8psp6kpb2vaqv",
      "stack": " at async Object.fetch (index.js:929:22)"
    }
  }

Container logs show no PATCH requests received.