What changed, and when
Local dev observability shipped in two stages. wrangler@4.114.0 (released 2026-07-23) first added the capability:
“Add local-dev observability”
wrangler@4.118.0 (released 2026-07-31) then flipped it on by default:
“Enable local observability capture by default in dev”
The same default-on behavior landed in the Cloudflare Vite plugin at version 1.50.0, via pull request #14944. Before 4.118.0, a developer had to explicitly opt in to get traces and console logs surfaced in the Local Explorer; after it, every wrangler dev or Vite-plugin dev session gets this automatically, whether or not anyone asked for it.
Structural Comparison Matrix
| Operational Aspect | Before (v4.113.0 and earlier) | After (v4.118.0+) |
|---|---|---|
| Default state | Opt-in only | Enabled automatically, no flag needed |
| Background processes | Just the dev server | Adds per-worker collector/streaming-tail services |
| Opt-out mechanism | N/A | X_LOCAL_OBSERVABILITY=false |
Fix it: opt out if it conflicts with your setup
Most single-worker setups don't need to do anything
If you run one Worker locally at a time, the added background services are unlikely to be noticeable. The opt-out matters most for multi-process dev-registry setups running several local workers simultaneously, where the extra per-worker services can compete for resources or interfere with existing tooling that already captures logs another way.
X_LOCAL_OBSERVABILITY=false wrangler devFor a persistent opt-out across every local session, set it in your shell profile or the project’s .env/.dev.vars file rather than prefixing every command by hand:
X_LOCAL_OBSERVABILITY=falseIf you want the feature but it isn’t showing traces, confirm the installed version first. This is version-gated, not a config toggle that exists on every Wrangler release:
wrangler --version
# needs wrangler 4.118.0+ or Cloudflare Vite plugin 1.50.0+Confirmed version
Sourced from cloudflare/workers-sdk’s packages/wrangler/CHANGELOG.md: the capability landed in wrangler@4.114.0 (2026-07-23), and the default-on switch in wrangler@4.118.0 (2026-07-31), corroborated by the Vite plugin’s own 1.50.0 changelog entry for pull request #14944. Browse more posts like this in the Dev Tools archive.
