# I have a fatal error I can't seem to fix, can anyone help?

**URL:** <https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571>\
**Category:** Using Concrete / Help\
**Created:** [October 31, 2025, 2:41pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571 "2025-10-31T14:41:40Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ittech](https://forums.concretecms.org/user_avatar/forums.concretecms.org/ittech/32/5178_2.png) [@ittech](https://forums.concretecms.org/u/ittech)\
**Post date:** [October 31, 2025, 2:41pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571/1 "2025-10-31T14:41:41Z")

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website is [heyerarchitect.com](http://heyerarchitect.com)

it started throwing whoops exception, we upgraded the PHP and it broke even more. getting this error now.

**Fatal error** : Uncaught Error: Undefined constant “Patchwork\Utf8\MB\_OVERLOAD\_STRING” in /home1/heyerarc/public\_html/updates/concrete5-8.5.5\_remote\_updater/concrete/vendor/patchwork/utf8/src/Patchwork/Utf8/Bootup.php:45 Stack trace: #0 /home1/heyerarc/public\_html/updates/concrete5-8.5.5\_remote\_updater/concrete/vendor/patchwork/utf8/src/Patchwork/Utf8/Bootup.php(26): Patchwork\Utf8\Bootup::initMbstring() #1 /home1/heyerarc/public\_html/updates/concrete5-8.5.5\_remote\_updater/concrete/bootstrap/start.php(19): Patchwork\Utf8\Bootup::initAll() #2 /home1/heyerarc/public\_html/updates/concrete5-8.5.5\_remote\_updater/concrete/dispatcher.php(36): require(‘/home1/heyerarc…’) #3 /home1/heyerarc/public\_html/concrete/bootstrap/configure.php(55): require(‘/home1/heyerarc…’) #4 /home1/heyerarc/public\_html/concrete/dispatcher.php(13): require(‘/home1/heyerarc…’) #5 /home1/heyerarc/public\_html/index.php(3): require(‘/home1/heyerarc…’) #6 {main} thrown in **/home1/heyerarc/public\_html/updates/concrete5-8.5.5\_remote\_updater/concrete/vendor/patchwork/utf8/src/Patchwork/Utf8/Bootup.php** on line **45**

any advice or pointers would be greatly appreciated.

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**Author:** ![JohntheFish](https://forums.concretecms.org/user_avatar/forums.concretecms.org/johnthefish/32/3767_2.png) [@JohntheFish](https://forums.concretecms.org/u/JohntheFish)\
**Post date:** [October 31, 2025, 3:13pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571/2 "2025-10-31T15:13:24Z")

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Best php for Concrete 8.5.5 would be php7.3. It won’t work with php8+

You should also update to 8.5.21 (current latest 8.5.x). There were some bugs that prevented the in-site updater from working some time early in 8.5.x that may also be playing a role in your problem

To get round it you can try a direct manual update to 8.5.21 - most reliable is by Replacing Original Concrete Directory.

Detailed instructions at

> **[Upgrading a Site](https://documentation.concretecms.org/9-x/developers/introduction/upgrading-concrete)**
>
> How to Upgrade Concrete CMS

get 8.5.21 from

> **[Concrete Version Archive](https://www.concretecms.org/download/archive)**

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<div class="post-metadata">

**Author:** ![ittech](https://forums.concretecms.org/user_avatar/forums.concretecms.org/ittech/32/5178_2.png) [@ittech](https://forums.concretecms.org/u/ittech)\
**Post date:** [October 31, 2025, 4:44pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571/3 "2025-10-31T16:44:14Z")

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Thank you for the response. I’ve tried the instructions and I fear I broke it more. I’m thinking the worst right now.

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<div class="post-metadata">

**Author:** ![JohntheFish](https://forums.concretecms.org/user_avatar/forums.concretecms.org/johnthefish/32/3767_2.png) [@JohntheFish](https://forums.concretecms.org/u/JohntheFish)\
**Post date:** [October 31, 2025, 5:31pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571/4 "2025-10-31T17:31:18Z")

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What php versions does your host have available?

When was it last working and what php version were you using? You could ask your host support to restore your hosting and database to their backup from the day before that.

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<div class="post-metadata">

**Author:** ![ittech](https://forums.concretecms.org/user_avatar/forums.concretecms.org/ittech/32/5178_2.png) [@ittech](https://forums.concretecms.org/u/ittech)\
**Post date:** [November 8, 2025, 8:06pm UTC](https://forums.concretecms.org/t/i-have-a-fatal-error-i-cant-seem-to-fix-can-anyone-help/9571/5 "2025-11-08T20:06:33Z")

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I just wanted to say thanks again. I was able to get it updated to the latest version of concrete and PHP. 🙂