Workers - Workers Observability now surfaces warning attributes on spans for non-fatal errors

Workers Observability now attaches warning attributes to spans for non-fatal telemetry issues. These attributes help you identify instrumentation issues.

When a warning is present, both attributes are set together:

• cloudflare.warning.type — An identifier indicating the type of warning condition.
• cloudflare.warning.message — A free-form, human-readable explanation of the warning condition.

For example, recording an entire webhook payload as a span attribute can exceed the span data limit:

export default {
	async fetch(request, env, ctx) {
		const payload = await request.text();

		return ctx.tracing.enterSpan("receive-webhook", (span) => {
			span.setAttribute("webhook.payload", payload);
			return new Response("Accepted", { status: 202 });
		});
	},
};

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext) {
    const payload = await request.text();

    return ctx.tracing.enterSpan("receive-webhook", (span) => {
      span.setAttribute("webhook.payload", payload);
      return new Response("Accepted", { status: 202 });
    });
  },
};

The Worker still returns 202 Accepted, but tracing drops the oversized attribute. The span includes cloudflare.warning.type set to span_data_limit_exceeded and a cloudflare.warning.message identifying the rejected attribute and its size.

For more information, refer to Warning attributes.