Cannot assign to read only property 'debug' of object '#<Object>'

[egorshar]

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?

Self-hosted/on-premise

Which SDK are you using?

@sentry/react

SDK Version

8.30.0

Framework Version

18.2.0

Link to Sentry event

No response

Reproduction Example/SDK Setup

initSentry({
  ...runtimeConfig.sentry,
  allowUrls: [
    document.location.origin,
    ...(appSettings.themeBuild.assetPrefix ? [appSettings.themeBuild.assetPrefix] : []),
  ],
  environment: runtimeConfig.env,
  integrations: [
    reactRouterV6BrowserTracingIntegration({
      stripBasename: true,
      useEffect,
      useLocation,
      useNavigationType,
      createRoutesFromChildren,
      matchRoutes,
    }),
    replayIntegration(),
    httpClientIntegration(),
  ],
  tracesSampleRate: 1.0,
  tracePropagationTargets: ['localhost', API_REGEXP],
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,
});

Steps to Reproduce

In exceptions reported by our clients, we observe an error where Sentry’s breadcrumbs integration seems to overwrite the console.debug method, but the method is unexpectedly readonly. This issue occurs before the full initialization of the Sentry client, and as a result, the events are not enriched with even basic browser metadata. Despite searching for similar issues, no solutions or explanations have been found online.

Do you have any insights into what might cause this or suggestions on how best to handle this case?

Expected Result

No error should be thrown

Actual Result

TypeError
Cannot assign to read only property 'debug' of object '#'

[lforst]

Thanks for writing in. We are patching the console object which normally is writable. Would you mind checking your codebase for any code that may make the consol object readonly (ie, frozen or writable: false or similar)?

[egorshar]

We observe this error occurring for approximately 1% of users (based on sentry transactions), while the rest use the site without such issues. This makes it seem unlikely that the problem lies in our code.

Initially, we considered potential causes like browser extensions or Google Tag Manager (GTM). However, GTM is loaded after the application’s initialization, so it’s unlikely to be the source. Regarding browser extensions, we cannot confirm since we lack metadata about them in Sentry. Additionally, most of our traffic comes from mobile devices rather than desktops, which reduces the likelihood of extension-related issues.

Currently, our plan is to wrap the Sentry initialization in a try/catch block and attempt to manually send the error data if the initialization fails.

[mydea]

Although the problem here is likely something other then the Sentry SDK, it does not hurt for us to handle this more gracefully and do not throw an error if we encounter such a problem! We'll try to adjust the SDK accordingly.