Title: generate Critical CSS failed
Last modified: May 25, 2026

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# generate Critical CSS failed

 *  [jvande](https://wordpress.org/support/users/jvande/)
 * (@jvande)
 * [2 weeks ago](https://wordpress.org/support/topic/generate-critical-css-failed-2/)
 * Complete error message, some pages were regenerated, this one repreatedly fails:
 * Cornerstone page
 * Something went wrong, which Jetpack Boost did not anticipate. An unexpected error
   occurred while trying to generate Critical CSS for the following page:
    - [https://staging.actonexchange.org/](https://staging.actonexchange.org/)
 * Please follow the troubleshooting steps below for the page.
    1. 1Visit the page.
    2. 2Verify that the page loads correctly.
    3. 3If it does, [try again](https://staging.actonexchange.org/wp-admin/admin.php?page=jetpack-boost#)
       to generate the Critical CSS.
    4. 4If the error still persist please contact [Jetpack Boost Support↗](https://wordpress.org/support/plugin/jetpack-boost/)
       with a copy of your error message.
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fgenerate-critical-css-failed-2%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Support [Josh (a11n)](https://wordpress.org/support/users/vitkory/)
 * (@vitkory)
 * [1 week, 5 days ago](https://wordpress.org/support/topic/generate-critical-css-failed-2/#post-18919793)
 * Howdy [@jvande](https://wordpress.org/support/users/jvande/),
 * Thanks for reaching out and for including the error details.
 * Since this is happening on a staging site (staging.actonexchange.org), the most
   likely cause is an access restriction preventing the Critical CSS generator from
   reaching the page. The generator needs to fetch your pages to analyze the CSS,
   so if the staging environment has any of the following, it won’t be able to complete:
    - HTTP authentication (username/password prompt)
    - IP allowlisting or firewall rules
    - A “coming soon” or maintenance mode plugin
    - The site not being publicly accessible
 * Could you confirm whether your staging site is publicly accessible? Try opening
   staging.actonexchange.org in a private/incognito browser window (while logged
   out) and see if the homepage loads without any login prompts or blocks.
 * If the staging site is intentionally restricted, Critical CSS generation won’t
   work there. You’d either need to temporarily open access while generating the
   CSS, or skip Critical CSS on staging and only use it on your production site.
 * Let us know what you find and we can go from there.
 *  Plugin Support [Stef (a11n)](https://wordpress.org/support/users/erania-pinnera/)
 * (@erania-pinnera)
 * [4 hours, 19 minutes ago](https://wordpress.org/support/topic/generate-critical-css-failed-2/#post-18931771)
 * Hi there, [@jvande](https://wordpress.org/support/users/jvande/),
 * Do you have updates about that, do you still need help? We usually close inactive
   threads after one week of no movement, but we want to make sure we’re all set
   before marking it as solved. Thanks!

Viewing 2 replies - 1 through 2 (of 2 total)

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to reply to this topic.

 * ![](https://ps.w.org/jetpack-boost/assets/icon.svg?rev=2818794)
 * [Jetpack Boost - Website Speed, Performance and Critical CSS](https://wordpress.org/plugins/jetpack-boost/)
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## Tags

 * [regenerate](https://wordpress.org/support/topic-tag/regenerate/)

 * 2 replies
 * 3 participants
 * Last reply from: [Stef (a11n)](https://wordpress.org/support/users/erania-pinnera/)
 * Last activity: [4 hours, 19 minutes ago](https://wordpress.org/support/topic/generate-critical-css-failed-2/#post-18931771)
 * Status: not resolved