Title: mysqli_set_charset and mkdir php errors
Last modified: April 3, 2022

---

# mysqli_set_charset and mkdir php errors

 *  Resolved [francoc30](https://wordpress.org/support/users/francoc30/)
 * (@francoc30)
 * [4 years, 4 months ago](https://wordpress.org/support/topic/mysqli_set_charset-and-mkdir-php-errors/)
 * Hi
    I manually ran Cache Preload to refresh the cache files and minify files.
   Multiple instances of the following error messages were recorded in the Error
   Log. This occurred every time the Cache Preloader was run. My site is a bilingual
   site. Is there any solution to these?
 * 20220403T025415: ccpst.com/wp-admin/install.php
    PHP Warning: mysqli_set_charset():
   Error executing query in /mysite_path/public_html/test/wp-includes/wp-db.php 
   on line 792
 * 20220403T023906: ccpst.com/index.php
    PHP Warning: mkdir(): File exists in /mysite_path/
   public_html/test/wp-content/plugins/wp-optimize/cache/file-based-page-cache-functions.
   php on line 119

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

 *  [Harshad](https://wordpress.org/support/users/bornforphp/)
 * (@bornforphp)
 * [4 years, 4 months ago](https://wordpress.org/support/topic/mysqli_set_charset-and-mkdir-php-errors/#post-15522769)
 * [@francoc30](https://wordpress.org/support/users/francoc30/) These are warnings,
   there’s nothing to worry about, it will not stop the functionality of your site
   or WP-Optimize plugin.
 * However, I’ll report this issue to our development team for further investigation.
    -  This reply was modified 4 years, 4 months ago by [Harshad](https://wordpress.org/support/users/bornforphp/).
 *  Thread Starter [francoc30](https://wordpress.org/support/users/francoc30/)
 * (@francoc30)
 * [4 years, 4 months ago](https://wordpress.org/support/topic/mysqli_set_charset-and-mkdir-php-errors/#post-15525324)
 * Yes they are warnings. But they still need to be corrected to avoid future problems.
   Thanks for letting the development team to know about these for fixes.

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

The topic ‘mysqli_set_charset and mkdir php errors’ 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/)

 * 2 replies
 * 2 participants
 * Last reply from: [francoc30](https://wordpress.org/support/users/francoc30/)
 * Last activity: [4 years, 4 months ago](https://wordpress.org/support/topic/mysqli_set_charset-and-mkdir-php-errors/#post-15525324)
 * Status: resolved