Title: Error: Warning: Undefined array key “enable_gzip”
Last modified: April 12, 2025

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# Error: Warning: Undefined array key “enable_gzip”

 *  Resolved [Bob](https://wordpress.org/support/users/bobk88/)
 * (@bobk88)
 * [12 months ago](https://wordpress.org/support/topic/error-warning-undefined-array-key-enable_gzip/)
 * I’m getting the following message at my home page:
 * Warning: Undefined array key “enable_gzip” in /usr/home/[username]/public_html/
   bobkarty.com/wp-content/plugins/wp-optimize/cache/class-wpo-page-cache.php on
   line 1500
 * When I go to the login page, I get the above error and three more. The first 
   is:
 * **Warning**: Cannot modify header information – headers already sent by (output
   started at /usr/home/[username]/public_html/bobkarty.com/wp-content/plugins/wp-
   optimize/cache/class-wpo-page-cache.php:1500) in **/usr/home/[username]/public_html/
   bobkarty.com/wp-login.php** on line **515**
 * The other two new messages are the same except the line numbers are 531 and 7137.
 * I’m unable to log into the site.
 * After disabling WP Optimize via FTP, I’m able to log in and the error messages
   go away.
 * Help, please!
 * WordPress: 6.7.2 Theme: 2022 WP Optimize 4.1.1
 * PHP: 8.2.28
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Ferror-warning-undefined-array-key-enable_gzip%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Plugin Support [Damilare](https://wordpress.org/support/users/deabiodun/)
 * (@deabiodun)
 * [12 months ago](https://wordpress.org/support/topic/error-warning-undefined-array-key-enable_gzip/#post-18414558)
 * Hi Bob!
   Sorry about the issue you’ve encountered.
 * Please confirm if the warning message remains when all your plugins are disabled
   except for WP-Optimize.
   Also send us your WPO system report. This can be generated
   as _**WP-Optimize > Settings > System status**_. You can safely send the report
   directly to us using [our contact form](https://teamupdraft.com/contact/). Make
   sure to reference this topic (support request) link in your message.
 * Looking forward to your response.
 * Regards.
 *  Thread Starter [Bob](https://wordpress.org/support/users/bobk88/)
 * (@bobk88)
 * [12 months ago](https://wordpress.org/support/topic/error-warning-undefined-array-key-enable_gzip/#post-18415372)
 * Thanks for the reply!
 * No, the warning does _not_ appear if WP Optimize is the only active plugin.
 * I re-enabled plugins one at a time and found that there appears to be a conflict
   between WP Optimize and “Far Future Expiry Header”: [https://wordpress.org/plugins/far-future-expiry-header/](https://wordpress.org/plugins/far-future-expiry-header/)
 * When Far Future Expiry Header is disabled, the errors go away.
 * Does WPO have a similar functionality to FFEH? If so, I can delete FFEH.
 * I sent the WPO System Report through your contact form as requested. Thanks!
 *  Plugin Support [Damilare](https://wordpress.org/support/users/deabiodun/)
 * (@deabiodun)
 * [12 months ago](https://wordpress.org/support/topic/error-warning-undefined-array-key-enable_gzip/#post-18416107)
 * The closest to FFEH is the Cache lifespan feature at _**WP-Optimize > Cache >
   Page cache > Cache Settings**_. This does not only extend the re-fetch time for
   site resources, but also for the site content.

Viewing 3 replies - 1 through 3 (of 3 total)

The topic ‘Error: Warning: Undefined array key “enable_gzip”’ is closed to new replies.

 * ![](https://ps.w.org/wp-optimize/assets/icon-256x256.png?rev=1552899)
 * [WP-Optimize – Cache, Compress images, Minify & Clean database to boost page speed & performance](https://wordpress.org/plugins/wp-optimize/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-optimize/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-optimize/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-optimize/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-optimize/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wp-optimize/reviews/)

 * 3 replies
 * 2 participants
 * Last reply from: [Damilare](https://wordpress.org/support/users/deabiodun/)
 * Last activity: [12 months ago](https://wordpress.org/support/topic/error-warning-undefined-array-key-enable_gzip/#post-18416107)
 * Status: resolved