Title: Fatal error on comment!!
Last modified: May 4, 2017

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# Fatal error on comment!!

 *  Resolved [etellewyn](https://wordpress.org/support/users/etellewyn/)
 * (@etellewyn)
 * [9 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-on-comment/)
 * Hi there, I noticed today that when I add a comment on our site, I get a white
   screen of death with this error:
 * Fatal error: Call to undefined function WP_Stream\mb_strtolower() in /home/wizzy/
   whtest2/wp-content/plugins/stream/connectors/class-connector-comments.php on 
   line 270
 * I’m currently logged in as admin, since I’m actively developing the site. I was
   just testing out my comment form, and good thing I did or I would not have noticed
   this until it was live!
 * Any idea how to fix?

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

 *  [Steve Bruner](https://wordpress.org/support/users/sbruner/)
 * (@sbruner)
 * [9 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-on-comment/#post-9109207)
 * You need to install/enable the mb_string PHP extension on your server.
 *  Thread Starter [etellewyn](https://wordpress.org/support/users/etellewyn/)
 * (@etellewyn)
 * [9 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-on-comment/#post-9113476)
 * [@sbruner](https://wordpress.org/support/users/sbruner/) Thanks!

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

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## Tags

 * [fatal error](https://wordpress.org/support/topic-tag/fatal-error/)

 * 2 replies
 * 2 participants
 * Last reply from: [etellewyn](https://wordpress.org/support/users/etellewyn/)
 * Last activity: [9 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-on-comment/#post-9113476)
 * Status: resolved