Sentry.lastEventId() doesn't work on SSR

[Asghar-Lyft]

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/browser

SDK Version

v10.37.0

Framework Version

v15.4.5

Link to Sentry event

I cannot provide URL at the moment, but this is the event ID 61acc185103343af8dcb1621464fd566 if it doesn't work let me know to provide you URL

Reproduction Example/SDK Setup

No response

Steps to Reproduce

I don't know! When an error happen in CSR (browser) everything works well, but for SSR (node) lastEventId doesn't work

Expected Result

Sentry should capture errors and the Sentry.lastEventId() should return a string and in the Sentry dashboard , we should find the event by searching id:EVENT_ID

Actual Result

Closely related to #19166

when I search id:EVENT_ID in Sentry dashboard in All Issues tab, it doesn't list the issue and

• For the id returned by captureException it shows Error lading chart data
• I copied captureUnderscoreErrorException to my repo and changed it to return event ID, in Sentry dashboard search leads to Error fetching releases error

I have a few different projects and they use different version of Next.js and Sentry, I don't want to add many details here, the important part is that

1. on Next.js v14.2.29 and SDK v8.3.0everything works well
2. but on Next.js v15.4.5 and SDK v10.37.0 only client-side error capturing works and server-side doesn't work well and I cannot find the event-id of the server-side error

Sentry.lastEventId() also doesn't work in SDK v10.37.0 but works on SDK v8.3.0

Additional Context

No response

Priority

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[linear]

JS-1657

[s1gr1d]

Hello and thanks for opening this issue! I created a PR which should fix that. I assumed that it's still a problem with the captureUnderscoreErrorException.

[s1gr1d]

Actually, I have a follow-up question here @Asghar-Lyft.

For the id returned by captureException it shows Error lading chart data
I copied captureUnderscoreErrorException to my repo and changed it to return event ID, in Sentry dashboard search leads to Error fetching releases error

Which error is actually thrown here? What do you expect here to be shown? And what code did you change/add here?

I'm wondering if you even need to use captureUnderscoreErrorException as the error is captured from the Sentry-wrapped getServerSideProps.

[s1gr1d]

Summary from my inspection so far where I set up an _error.ts page and threw an error on another page within getServerSideProps:

1. First capture (creates Event ID):
   • When getServerSideProps throws an error, it's caught by withErrorInstrumentation wrapper
   • Mechanism: auto.function.nextjs.wrapped
   • This is the error that actually gets sent to Sentry
2. Second capture attempt (another Event ID):
   • When Next.js renders the _error page, captureUnderscoreErrorException tries to capture the same error object again
   • Mechanism: auto.function.nextjs.underscore_error
   • This is prevented by the deduplication check (checkOrSetAlreadyCaught)
   • The event is not sent to Sentry

So captureUnderscoreErrorException returns an eventId but it's the one of the filtered error.

What we could do here: Within captureUnderscoreException, check if this event was already captured and return the previous event ID (we don't need to create a new one). We'll discuss this internally. captureUnderscoreErrorException should probably only capture errors that haven't already been captured by the wrapper functions. Would that make sense for you?