Impacted plugin

Boost

Quick summary

Our user reported seeing a "Failed to generate Critical CSS" error when Jetpack Boost was automatically attempting to regenerate critical CSS. This error appeared coupled with a 403 error.

I noticed a set of errors on the Jetpack page that suggest a connection issue:

See here: 3435f-pb/

The Jetpack Connection looks good (there are some inconsistencies in the Incremental Sync). The domain is connected using A records via Cloudflare.

Steps to reproduce

1. Open the Jetpack Boost page
2. Wait for Boost to "Automatically Optimize CSS Loading"
3. The error occurs after a short wait.

A clear and concise description of what you expected to happen.

Jetpack Boost should generate critical CSS without producing an error.

What actually happened

Instead, there is an error when Boost attempts to generate critical CSS. See here (around 45 seconds):

There were no corresponding errors or warnings in my browser Console when this occurred.

Impact

One

Available workarounds?

No but the platform is still usable

Platform (Simple and/or Atomic)

Atomic

Logs or notes

Chat: 8037651-zen
Follow-up ticket: 8037799-zen

I tested this on the following:

• macOS 14.4.1
• Firefox Developer Edition 126.0b3