vitest-pool-workers: green runs are flooded with `disconnected: peer disconnected without gracefully ending TLS session` when tests fetch real TLS endpoints

[mishushakov]

What versions & operating system are you using?

@cloudflare/vitest-pool-workers 0.18.7, miniflare 4.20260721.0, workerd 1.20260721.1, vitest 4.1.8, Node 24, Linux (GitHub Actions ubuntu-22.04) and macOS.

Describe the Bug

When a test suite running under vitest-pool-workers makes real fetch() calls to external HTTPS endpoints, workerd repeatedly logs an internal exception with a full (unsymbolized) stack trace, even though every test passes:

exception = kj/compat/tls.c++:429: disconnected: peer disconnected without gracefully ending TLS session
stack: .../node_modules/@cloudflare/workerd-linux-64/bin/workerd@364fe50 .../bin/workerd@53d0120 ... (~18 frames)

This happens whenever the remote server or a load balancer closes an idle keepalive connection without sending a TLS close_notify — normal internet behavior that HTTP clients are expected to tolerate silently (undici, Bun, and Deno all discard the same event). No request is in flight on the connection, so nothing fails; it's purely log noise, but with the stack trace it dominates the output of an otherwise green run (10+ occurrences in a ~90s suite).

Real-world example (public CI log from the E2B JS SDK integration suite, all 393 tests passing): https://github.com/e2b-dev/E2B/actions/runs/30017080220/job/89239801004

There is no user-side hook to filter it: the pool installs its own handleStructuredLogs and spreads SHARED_MINIFLARE_OPTIONS into the final Miniflare options itself, so the miniflare key in the vitest config can't override log handling.

Expected behavior

The message is filtered like its siblings. ignoreMessages in packages/vitest-pool-workers/src/pool/index.ts already suppresses the equivalent non-TLS shapes — disconnected: operation canceled, disconnected: WebSocket peer disconnected, etc. — under the comment "this is normal operation and really shouldn't error". The TLS variant belongs in the same list:

"disconnected: peer disconnected without gracefully ending TLS session",

Please provide a link to a minimal reproduction

Any worker test that opens a TLS connection to a server that drops idle connections without close_notify reproduces it; the CI log linked above is a live example. I'll open a one-line PR adding the message to ignoreMessages.

[workers-devprod]

Note

This is an automated, advisory triage report generated by workers-devprod. It is not an official maintainer response — a maintainer will follow up.

🤖 Automated triage report

Issue Triage: #14820

Summary

vitest-pool-workers floods otherwise-green test runs with disconnected: peer disconnected without gracefully ending TLS session exceptions (plus full stack traces) when tests make real fetch() calls to TLS endpoints that close idle connections without close_notify.

Classification

• Type: Bug
• Component: packages/vitest-pool-workers
• Severity: Low
• Has Reproduction: Yes (described repro + live public CI log link; no clonable minimal repo, but the cause and fix are pinpointed)
• Quality: Complete

Findings

• Created: 2026-07-23
• Author: mishushakov
• Version: @cloudflare/vitest-pool-workers 0.18.7, miniflare 4.20260721.0, workerd 1.20260721.1, vitest 4.1.8, Node 24 (Linux GitHub Actions ubuntu-22.04 and macOS)
• Labels: none
• Comments: 0

Analysis

• Clearly a vitest-pool-workers tooling issue, not a runtime bug: the noise comes from the pool's own log handling. The reporter identifies the exact location — ignoreMessages in packages/vitest-pool-workers/src/pool/index.ts — which already suppresses sibling shapes (disconnected: operation canceled, disconnected: WebSocket peer disconnected) under a "this is normal operation and really shouldn't error" comment.
• The proposed fix is a one-line addition of the string "disconnected: peer disconnected without gracefully ending TLS session" to that ignoreMessages list. This matches the existing pattern and is very low risk.
• The reporter notes users cannot work around it themselves because the pool installs its own handleStructuredLogs and spreads SHARED_MINIFLARE_OPTIONS, so the miniflare key in the vitest config cannot override log handling — reinforcing that the fix belongs in the pool.
• Impact is cosmetic (log noise only — no test fails, no request is in flight), but it is disruptive: 10+ stack-trace dumps in a ~90s run drown out real output. A live public CI log (E2B JS SDK suite, all 393 tests passing) is linked as evidence.
• The reporter states they will open a one-line PR, so this is best kept open as the tracking issue for that contribution.

Recommendation

Status: KEEP OPEN

Reasoning: This is a valid, well-scoped bug in vitest-pool-workers with a correctly-diagnosed root cause and an obvious, low-risk one-line fix that matches an existing pattern. The reporter has offered to submit the PR, so the issue should remain open to track it.

Action: Confirm the fix approach (adding the TLS message to the ignoreMessages allowlist in packages/vitest-pool-workers/src/pool/index.ts) and accept the reporter's offered PR, or apply the one-line change directly. Label as a vitest / bug item.

Suggested Labels: vitest, bug

Suggested Comment

Thanks for the detailed report — and for pinpointing the exact spot. You're right that this belongs alongside the other disconnected: shapes already suppressed in ignoreMessages in packages/vitest-pool-workers/src/pool/index.ts, since it's benign log noise from idle TLS connections being closed without close_notify. A one-line PR adding "disconnected: peer disconnected without gracefully ending TLS session" to that list would be very welcome — please tag this issue in it and we'll get it reviewed.

Structured summary (JSON)

{
  "issueNumber": 14820,
  "title": "vitest-pool-workers: green runs are flooded with `disconnected: peer disconnected without gracefully ending TLS session` when tests fetch real TLS endpoints",
  "githubUrl": "https://github.com/cloudflare/workers-sdk/issues/14820",
  "recommendation": "KEEP OPEN",
  "difficulty": "easy",
  "reasoning": "Valid, well-scoped log-noise bug in vitest-pool-workers with a correctly diagnosed root cause and an obvious one-line fix that matches an existing ignoreMessages pattern. The reporter has offered to submit the PR.",
  "suggestedAction": "Accept the reporter's one-line PR (or apply it directly) adding the TLS disconnect message to the ignoreMessages allowlist in packages/vitest-pool-workers/src/pool/index.ts.",
  "hasSuggestedComment": true,
  "suggestedLabels": ["vitest", "bug"]
}