Cloudflare Durable Object instrumentDurableObjectWithSentry throwing errors

[danieljvdm]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/cloudflare

SDK Version

9.40.0

Framework Version

No response

Link to Sentry event

No response

Reproduction Example/SDK Setup

No response

Steps to Reproduce

export const CallAgent = CallAgentBase;

export const CallAgent = Sentry.instrumentDurableObjectWithSentry(
  () => ({
    dsn: "REDACTED",
    tracesSampleRate: 1.0,
  }),
  CallAgentBase
);

I get no errors with the first line, I get

✘ [ERROR] Uncaught Error: #<Promise> 


✘ [ERROR] Uncaught Error: #<Promise> 


✘ [ERROR] Uncaught Error: #<Promise> 


✘ [ERROR] Uncaught Error: #<Promise> 


✘ [ERROR] Uncaught Error: #<Promise> 

From wrangler with the second line.

Additional context is that this is wrapping a cloudflare agent (which is just a DO)

Expected Result

No errors when using instrumentDurableObjectWithSentry

Actual Result

Uncaught error

[linear]

JS-754 Cloudflare Durable Object instrumentDurableObjectWithSentry throwing errors

[danieljvdm]

I debugged this with claude code and got the following:

I’ve identified the root cause: Sentry’s instrumentation is wrapping the sql method inherited from the Agent base class, but the wrapping is breaking the method’s return value. The sql method should return an array, but after wrapping, it’s returning something non-iterable (likely a Promise).

⸻

The Problem

1. The Agent class has a sql method that uses template literals and returns an array
2. Sentry wraps all methods on the Durable Object instance, including inherited ones
3. The wrapper uses Reflect.apply inside an async scope, which may cause the return value to become a Promise
4. When alarm() tries to iterate over the result with for (const row of result || []), it fails because Promises aren’t iterable

I'm not sure what the best fix is, we could add method === 'sql' to https://github.com/getsentry/sentry-javascript/blob/master/packages/cloudflare/src/durableobject.ts#L213 or wrapMethodWithSentry would need to be updated to support the synchronous callback.

Agents sql method: https://github.com/cloudflare/agents/blob/main/packages/agents/src/index.ts#L364

[AbhiPrasad]

We should update wrapMethodWithSentry not async everything. @danieljvdm would you be interested in opening a PR?

[aroman]

Sentry's DurableObject integration will silently break everyone's code unless it so happens every single one of their DurableObject's methods is async. Most of our are not. I can't believe this shipped.