Title: Fatal Error during Build process
Last modified: August 22, 2016

---

# Fatal Error during Build process

 *  Resolved [bschneider94](https://wordpress.org/support/users/bschneider94/)
 * (@bschneider94)
 * [11 years, 3 months ago](https://wordpress.org/support/topic/fatal-error-during-build-process/)
 * Hi All,
 * I am trying to build a package but keep recieving this error:
 * ‘Fatal error: Call to undefined function mb_strlen() in /home/adeptbs/public_html/
   wp-content/plugins/duplicator/classes/utility.php on line 55’
 * Can anyone help with this error please?
 * Thanks
 * Ben
 * [https://wordpress.org/plugins/duplicator/](https://wordpress.org/plugins/duplicator/)

Viewing 6 replies - 1 through 6 (of 6 total)

 *  Thread Starter [bschneider94](https://wordpress.org/support/users/bschneider94/)
 * (@bschneider94)
 * [11 years, 3 months ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5825956)
 * Forgot to mention…
 * Line 55 in that file is the following:
 * ‘fseek($f, -mb_strlen($chunk, ‘8bit’), SEEK_CUR);’
 * Thanks
 * Ben
 *  [Cory Lamle](https://wordpress.org/support/users/corylamleorg/)
 * (@corylamleorg)
 * [11 years, 3 months ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826167)
 * Looks like your missing an extension:
 * [http://php.net/manual/en/mbstring.installation.php](http://php.net/manual/en/mbstring.installation.php)
 * I’ll see if I can perform a check or find an alternate approach for this…
 * Cheers~
 *  [Azbuildstuff](https://wordpress.org/support/users/azbuildstuff/)
 * (@azbuildstuff)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826333)
 * any remedy yet?
 *  [Cory Lamle](https://wordpress.org/support/users/corylamleorg/)
 * (@corylamleorg)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826335)
 * Hey Azbuildstuff,
 * If you can give the developer version a try it will have the validation check
   to prevent the error, however to fix the underlying issue you need to get mbstring
   installed on your system. The very latest version (0.5.13) can be found by following
   these instructions:
 *  -> Browse to [http://wordpress.org/extend/plugins/duplicator/developers/](http://wordpress.org/extend/plugins/duplicator/developers/)
   -
   > Look for the section “Other Versions” -> Click on “Development Version” and
   download the zip plugin file -> Uninstall your current version and install this
   one
 * Let me know if this solves your issue…
 * Thanks
 *  [nova077](https://wordpress.org/support/users/nova077/)
 * (@nova077)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826336)
 * use this to enable the mblen:
 * [http://www.knowledgebase-script.com/kb/article/how-to-enable-mbstring-in-php-46.html](http://www.knowledgebase-script.com/kb/article/how-to-enable-mbstring-in-php-46.html)
 *  [Cory Lamle](https://wordpress.org/support/users/corylamleorg/)
 * (@corylamleorg)
 * [11 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826339)
 * Thanks for the link!

Viewing 6 replies - 1 through 6 (of 6 total)

The topic ‘Fatal Error during Build process’ is closed to new replies.

 * ![](https://ps.w.org/duplicator/assets/icon-256x256.png?rev=2906985)
 * [Duplicator - Backups & Migration Plugin - Cloud Backups, Scheduled Backups, & More](https://wordpress.org/plugins/duplicator/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/duplicator/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/duplicator/)
 * [Active Topics](https://wordpress.org/support/plugin/duplicator/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/duplicator/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/duplicator/reviews/)

 * 6 replies
 * 4 participants
 * Last reply from: [Cory Lamle](https://wordpress.org/support/users/corylamleorg/)
 * Last activity: [11 years, 1 month ago](https://wordpress.org/support/topic/fatal-error-during-build-process/#post-5826339)
 * Status: resolved