When I try to upgrade to PHP 8,0 (from 7,1,33), my blog crashes

[Jean-Pierre Martel]

The error message is this one (with the Contempt theme) :

Fatal error: Uncaught Error: Undefined constant "wp_10867994_" in /home/customer/www/jpmartel.quebec/public_html/wp-config.php:61

Stack trace:
#0 /home/customer/www/jpmartel.quebec/public_html/wp-load.php(37): require_once()
#1 /home/customer/www/jpmartel.quebec/public_html/wp-blog-header.php(13): require_once('/home/customer/...')
#2 /home/customer/www/jpmartel.quebec/public_html/index.php(17): require('/home/customer/...')
#3 {main} thrown in /home/customer/www/jpmartel.quebec/public_html/wp-config.php on line 61

[desrosj]

Hi @jean-pierre-martel,

Welcome to Trac!

Please be advised, WordPress 5.5.x does not (and will not) support PHP 8.

WordPress 5.6, due out at the end of November, will be PHP 8 compatible. However, PHP 8 is a very large update with many breaking changes. There are a number of considerations to be made prior to upgrading.

Stay tuned the the make.wordpress.org/core blog in the next week for more information.

It’s also likely that your plugins and theme will require updates prior to upgrading to PHP 8 as well.

I’m going to close this ticket out because you are reporting specifically against WordPress 5.5. If you’d like to help test, please update to WordPress 5.6 using the beta tester plugin. However, that is not recommended in production.

[SergeyBiryukov]

Thanks for the report! Just noting that there is no wp_10867994_ constant in WordPress core, this appears to be something specific to your environment.

At a glance, it looks like the string on line 61 of the wp-config.php file is missing quotes and should probably be 'wp_10867994_' instead of just wp_10867994_.

As noted above, WordPress 5.5.3 is not compatible with PHP 8, but ​WordPress 5.6 aims to be (as much as possible).

[desrosj]

I do have one guess as to what the error is. One of the changes in PHP 8 is that the new default error reporting level is all. It’s likely this error was being silently discarded on PHP 7 and that change has caused the error to be surfaced. See ​https://php.watch/versions/8.0/error-display-E_ALL.