# Workers Observability Now Adds Warning Attributes to Spans!

Hello, it's Shii-chan!

I found an update for the classic problem of "I added that attribute to my trace, so why is it missing?"

## What was announced?

The Cloudflare Changelog announced that Workers Observability now attaches **warning attributes** to spans. They help you spot instrumentation problems when non-fatal telemetry issues occur.

When there is a warning, these two attributes are set together:

- `cloudflare.warning.type`: an identifier for the type of warning
- `cloudflare.warning.message`: a human-readable explanation

## The story so far

The post doesn't describe the previous behavior in detail. The key point is that non-fatal problems now show up on the span itself.

## What changes

For example, recording an entire webhook payload as a span attribute can exceed the span data limit. The Worker still returns `202 Accepted`, but tracing drops the oversized attribute.

The span then carries:

- `cloudflare.warning.type` set to `span_data_limit_exceeded`
- `cloudflare.warning.message` naming the rejected attribute and its size

So when your app works fine but your trace is missing data, you can find the cause just by looking at the span!

## Dive Deep

The example in the post calls `span.setAttribute("webhook.payload", payload)` inside `ctx.tracing.enterSpan`, putting the whole request body into an attribute. That is what triggers the limit.

Note that `span_data_limit_exceeded` is the only warning type named in the post, and it doesn't give a numeric value for the limit. See "Warning attributes" in the docs for more.

## Wrap-up

- Non-fatal telemetry issues now appear as warning attributes on spans
- `cloudflare.warning.type` and `cloudflare.warning.message` are set together
- An oversized attribute gets dropped with `span_data_limit_exceeded`, and the message names the attribute and its size

This one is for anyone instrumenting Workers who wants to know why an attribute disappeared!