Title: Error 500 when installing plugin on apache
Last modified: October 20, 2025

---

# Error 500 when installing plugin on apache

 *  [Pete (a11n)](https://wordpress.org/support/users/dilirity/)
 * (@dilirity)
 * [7 months, 3 weeks ago](https://wordpress.org/support/topic/error-500-when-installing-plugin-on-apache/)
 * Logs
 *     ```wp-block-code
       [Mon Oct 20 14:21:47.944360 2025] [core:alert] [pid 44:tid 281472208335136] [client 172.17.0.1:56729] /var/www/html/.htaccess: Invalid command 'Header', perhaps misspelled or defined by a module not included in the server configuration
       ```
   
 * `.htaccess` declaration
 *     ```wp-block-code
       # SGO Unset Vary  Header unset Vary# SGO Unset Vary END
       ```
   
 * This should first check if the `mod_headers` module is present. Otherwise, it
   breaks the entire site if it isn’t.
    -  This topic was modified 7 months, 3 weeks ago by [Pete (a11n)](https://wordpress.org/support/users/dilirity/).
      Reason: added log entry

Viewing 1 replies (of 1 total)

 *  Plugin Support [Ivaylo Stoyanov](https://wordpress.org/support/users/ivaylostoyanov/)
 * (@ivaylostoyanov)
 * [7 months, 2 weeks ago](https://wordpress.org/support/topic/error-500-when-installing-plugin-on-apache/#post-18693795)
 * Hello [@dilirity](https://wordpress.org/support/users/dilirity/),
 * The information regarding this issue has been relayed to our developers, who 
   will review it to implement a solution that prevents similar issues in the future.
 * You can follow the plugin updates to stay informed about when this matter is 
   addressed.
 * Best regards,
 * Ivaylo Stoyanov

Viewing 1 replies (of 1 total)

The topic ‘Error 500 when installing plugin on apache’ is closed to new replies.

 * ![](https://ps.w.org/sg-cachepress/assets/icon-256x256.gif?rev=2971889)
 * [Speed Optimizer - The All-In-One Performance-Boosting Plugin](https://wordpress.org/plugins/sg-cachepress/)
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 * 1 reply
 * 2 participants
 * Last reply from: [Ivaylo Stoyanov](https://wordpress.org/support/users/ivaylostoyanov/)
 * Last activity: [7 months, 2 weeks ago](https://wordpress.org/support/topic/error-500-when-installing-plugin-on-apache/#post-18693795)
 * Status: not resolved