We are phasing out support for domain fronting on traffic that passes through our CDN. As part of this change, all incoming connections to the following endpoints must include a valid Server Name Indication (SNI) during TLS negotiation:
* app.launchdarkly.com
* sdk.launchdarkly.com
* clientsdk.launchdarkly.com
Brownout Test Scheduled
🗓️ Date: Jul 23, 2025
🕐 Time: 1:00 PM – 3:00 PM Pacific Time
During this two-hour brownout test window, any request that does not include a valid SNI will be rejected with an HTTP 421 (Misdirected Request) response code.
We've already worked with impacted customers and currently observe only trace levels of non-compliant traffic, primarily from automated sources such as bots and crawlers. However, we recommend all customers monitor their services during this time, especially if you use a proxy between your applications and LaunchDarkly.
What to Do If You See Issues
If you encounter a 421 response for what you believe is a valid request:
1. Check SNI Configuration: Ensure your tools, libraries, or proxies are correctly configured to include SNI during TLS handshakes.
2. Contact Support: If the issue persists, reach out to our support team. Please include details such as:
* The endpoint being accessed
* The tools, SDKs, libraries, or proxies involved
* Logs or error messages, if available
Posted on
Jul 09, 2025 - 15:29 PDT