Title: Error when converting to WebP
Last modified: April 27, 2026

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# Error when converting to WebP

 *  [duber777](https://wordpress.org/support/users/duber777/)
 * (@duber777)
 * [3 weeks, 5 days ago](https://wordpress.org/support/topic/error-when-converting-to-webp/)
 * Hello.
 * PHP 8.5.5, WP 6.9.4, WEB Server IIS, Theme Hello Elementor.
 * When using the plugin with the “WebP or AVIF replacement of images and contents”
   mode enabled, I get an error in the PHP log: PHP Warning: Cannot use string as
   array in ……….\wp-content\plugins\plus-webp\lib\class-pluswebp.php on line 521
 * It appears even when uploading a single jpg image to the media library using 
   the standard WordPress mechanism with third-party plugins disabled. Despite this,
   the webp file is being created successfully.

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 * ![](https://ps.w.org/plus-webp/assets/icon-256x256.png?rev=2087314)
 * [Plus WebP or AVIF](https://wordpress.org/plugins/plus-webp/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/plus-webp/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/plus-webp/)
 * [Active Topics](https://wordpress.org/support/plugin/plus-webp/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/plus-webp/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/plus-webp/reviews/)

 * 0 replies
 * 1 participant
 * Last reply from: [duber777](https://wordpress.org/support/users/duber777/)
 * Last activity: [3 weeks, 5 days ago](https://wordpress.org/support/topic/error-when-converting-to-webp/)
 * Status: not resolved