Title: PHP Warning: hex2bin(): Input string must be hexadecimal string
Last modified: September 17, 2025

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# PHP Warning: hex2bin(): Input string must be hexadecimal string

 *  [infocompassclass](https://wordpress.org/support/users/infocompassclass/)
 * (@infocompassclass)
 * [8 months, 3 weeks ago](https://wordpress.org/support/topic/php-warning-hex2bin-input-string-must-be-hexadecimal-string/)
 * Has anyone else seen this kind of PHP warning from the plugin? I haven’t noticed
   issues from my users, but was curious if it can be resolved. It’s been happening
   since before version 2.1.0.
 * PHP message: PHP Warning: hex2bin(): Input string must be hexadecimal string 
   in /var/www/domain.com/htdocs/wp-content/plugins/wp-remote-users-sync/inc/api/
   class-wprus-api-abstract.php on line 856; PHP message: Wprus_Api_Abstract->decrypt_data
   on line 199: Could not decrypt data: invalid bundle” while reading response header
   from upstream, client: IP , server: domain.com, request: “POST /wp-admin/admin-
   ajax.php HTTP/2.0”, upstream: “fastcgi://unix:/var/run/php/php82-fpm-domain.com.
   sock:”, host: “domain.com”, referrer: “[https://domain.com/wp-login.php&#8221](https://domain.com/wp-login.php&#8221);
    -  This topic was modified 8 months, 3 weeks ago by [infocompassclass](https://wordpress.org/support/users/infocompassclass/).

The topic ‘PHP Warning: hex2bin(): Input string must be hexadecimal string’ is closed
to new replies.

 * ![](https://ps.w.org/wp-remote-users-sync/assets/icon-256x256.png?rev=2260728)
 * [WP Remote Users Sync](https://wordpress.org/plugins/wp-remote-users-sync/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-remote-users-sync/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-remote-users-sync/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-remote-users-sync/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-remote-users-sync/unresolved/)
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 * 0 replies
 * 1 participant
 * Last reply from: [infocompassclass](https://wordpress.org/support/users/infocompassclass/)
 * Last activity: [8 months, 3 weeks ago](https://wordpress.org/support/topic/php-warning-hex2bin-input-string-must-be-hexadecimal-string/)
 * Status: not resolved