feat(upload): Mention feature flag

[jjbayer]

Clarified the requirement for the projects:resumable-uploads feature flag in the upload endpoint warning.

DESCRIBE YOUR PR

Mention required feature flag for resumable uploads.

IS YOUR CHANGE URGENT?

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Select exactly one option. For deadlines, replace YYYY-MM-DD with the due date. You can update this information later by editing the PR description.

• Urgent deadline (GA date, etc.): 2026-10-19
• Other deadline: YYYY-MM-DD
• No deadline: Not urgent, can wait up to 1 week+

SLA

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• Please give the docs team up to 1 week to review your PR unless you've supplied a deadline.

Thanks in advance for your help!

PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

LEGAL BOILERPLATE

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

EXTRA RESOURCES

• Sentry Docs contributor guide

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
develop-docs	Ready	Preview	Oct 19, 2026 7:45am UTC

1 Skipped Deployment

Project	Deployment	Actions	Updated
sentry-docs	Ignored		Oct 19, 2026 7:45am UTC

[cursor]

The change adds a feature-flag warning on the resumable uploads developer page. The plan checks that warning on the live page, client errors, and 404s. An issue escalates when the page is missing or the error rate rises.

Rollout complete

Services: develop-docs.

Plan

What changed

Readers of the resumable uploads page now see a warning that the endpoint needs projects:resumable-uploads.
The change is live after develop-docs deploys.
Vercel production mapping and the develop-docs/ path both select that service.

Risk

Broken MDX can 404 this page, so readers miss the flag requirement.
A render fault in the warning can raise client errors on this page.
The blast radius is this developer docs page. Ingest of uploads does not change.

Intended effect

This is a docs wording change. No counter increments when the new warning appears.
Fetch the live page after deploy. Confirmed means the body includes projects:resumable-uploads.
Absent means the page still returns not found, or the old protocol warning remains.

Signal	Baseline	Rule	Source
Live resumable uploads page	Page Not Found	Body must include projects:resumable-uploads	GET https://develop.sentry.dev/sdk/telemetry/attachments/upload/ at 2026-10-19T07:44Z

Regression watch

A bad MDX compile can 404 this page. A render fault can raise client errors.
Error share may be noisy from day to day. Page-load volume may vary by weekday.

Signal	Baseline	Rule	Source
Client error share vs docs.page.load	0.66-2.35%	Do not rise above 2.35%	Sentry sentry/develop-docs, errors environment:production count over docs.page.load sum, 2026-10-17T07:44:00Z to 2026-10-19T07:44:00Z. Last 24h: 22 errors / 938 loads. Prior 24h: 4 errors / 604 loads.
docs.page.not_found share vs docs.page.load	0.11-0.33%	Do not rise above 0.33%	Sentry sentry/develop-docs metrics environment:production, 2026-10-17T07:44:00Z to 2026-10-19T07:44:00Z. Last 24h: 1 / 938. Prior 24h: 2 / 604.
docs.page.load volume	0.42-0.65 per minute	Do not fall below 0.42 per minute	Sentry sentry/develop-docs metric docs.page.load sum, environment:production, 2026-10-17T07:44:00Z to 2026-10-19T07:44:00Z. Last 24h: 938. Prior 24h: 604.

If 404 share or error share rises, inspect the live resumable uploads page and sibling attachments pages.

Not observable

Pageload traces for /sdk/telemetry/attachments/upload/ timed out, so this plan has no path-sliced latency baseline.
docs.page.load was not grouped by path.
none of those gaps is a substitute for the live page fetch above.

[cursor]

Verified in production

• The live upload guide includes the feature-flag warning.