Classic SEO is not compatible with PHP 8

I wanted to test today, with full anticipation my website with ClassicPress 1.5. Unfortunately Classic SEO (latest version) is not compatible with PHP 8.

PHP 8.0.26
Classic Press Version 1.5.0
Classic Seo Version 2.0.1

While activating the Plugin i get this error on my dev instance.

Fatal error: Uncaught TypeError: filter_var(): Argument #3 ($options) must be of type array|int, string given in /home//www//wp-content/plugins/classicpress-seo/includes/helpers/class-param.php:56 Stack trace: #0 /home//www//wp-content/plugins/classicpress-seo/includes/helpers/class-param.php(56): filter_var('error_scrape', 516, '') #1 /home//www//wp-content/plugins/classicpress-seo/classicpress-seo.php(314): Classic_SEO\Helpers\Param::request('action') #2 /home//www//wp-content/plugins/classicpress-seo/classicpress-seo.php(188): Classic_SEO->init_actions() #3 /home//www//wp-content/plugins/classicpress-seo/classicpress-seo.php(164): Classic_SEO->setup() #4 /home//www//wp-content/plugins/classicpress-seo/classicpress-seo.php(440): Classic_SEO::get() #5 /home//www//wp-content/plugins/classicpress-seo/classicpress-seo.php(444): cpseo() #6 /home//www//wp-admin/includes/plugin.php(2138): include('/home//...') #7 /home//www//wp-admin/plugins.php(176): plugin_sandbox_scrape('classicpress-se...') #8 {main} thrown in /home//www/**/wp-content/plugins/classicpress-seo/includes/helpers/class-param.php on line 56

I think the plugin is very good, but I’m not sure if the plugin is still actively maintained. Do you have any information about it?

I was able to solve the problem as follows: In /wp-content/plugins/classicpress-seo/includes/helpers/class-param.php are four methods in which $filter = FILTER_DEFAULT, $flag = ‘’ is defned. A 0 must be used, not an empty string.

After I made this change I could activate and deactivate the plugin and activate it again. All the previous tests worked. Do more tests. Hope that tomorrow I can use PHP 8 on the productive system.


the promised update would be fine. …

I like the plugin …


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We have a new version 2.1.0 coming out soon with PHP 8 compatibility. If you would like to test it, that would be very helpful before we release it.

You can download zip here.

Private repo I guess, it responds with 404. Would love to test.

I fixed the link. Repo is public, this release is still a draft, so it’s not public.

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Classic SEO v2.1.0 is out. You should be able to update now. If you have any issues, please start a new topic to report.