Help Test PHP 8.0 Compatibility in v1.5.0-RC1

Originally published at: Help Test PHP 8.0 Compatibility in v1.5.0-RC1 | ClassicPress

Help test ClassicPress v1.5.0-RC1 with PHP 8.0 and report all issues. Your help is greatly appreciated.

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I copied my entire installation of ClassicPress 1.4.4 from my production VPS server into my new development virtual machine running PHP 8.1 and everything seems to work fine after I upgrade to 1.5.0-rc1. I am able to post a comment and access the admin panel.

[email protected]:~$ php --version
PHP 8.1.12 (cli) (built: Nov 10 2022 02:42:46) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.12, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.12, Copyright (c), by Zend Technologies

My development VM runs Debian Sid/Unstable with PHP 8.1. I will wait for ClassicPress 1.5 to come out before I upgrade my VPS machine from Ubuntu 20.04 LTS to 22.04 LTS.

This release doesn’t yet provide PHP 8.1 support. There will be issues. At this time, only PHP 8.0 is supported.

testing this RC on a multisite setup with several plugins on a PHP 8.0.26 and debugging to true with error logging.
I am on hosting with the Plesk panel.
No errors so far, and everything works smoothly.


Below are my test results. Except for ClassicSEO plugin, all seems to be working fine.

Server details

VPS : Intel Xeon, 16GB RAM, 4Core
Debian : 11
Apache : 2.4.54
MySQL : 8.0.31

  • Fresh install

CP version : 1.4.4
PHP : 7.4.33


  • Limit Login Reloaded
  • Classic SEO (btw - throws an error when trying to watch details)


  • basic Security hardening
  • Added the MAKE theme

Installation now is more or less a basic production installation.

  • Upgrade to v1.5.0-RC1 (migration plugin)
  • tested creating page + post using PHP 7.4.x
  • installed plugin (cpcompatibility, older version)
  • installed plugin WP Fastest Cache
  • Switched to Php 8.0.25

Update cpcompatibility failed: “Update Failed: Internal Server Error”, error log shows it’s Classic Seo causing it:
classicpress-seo/includes/module/class-manager.php(43): Classic_SEO\Helpers\Conditional::is_heartbeat()\n#3

After removing it cpcompatibility worked again and updated. Downloaded new version from CP SEO from the CP website, installation fails (changed username/domain in below). This is, I’d say, an essential plugin:

Fatal error: Uncaught TypeError: filter_var(): Argument #3 ($options) must be of type array|int, string given in /home/user/domains/ Stack trace: #0 /home/user/domains/ filter_var() #1 /home/user/domains/ Classic_SEO\Helpers\Param::request() #2 /home/user/domains/ Classic_SEO->init_actions() #3 /home/user/domains/ Classic_SEO->setup() #4 /home/user/domains/ Classic_SEO::get() #5 /home/user/domains/ cpseo() #6 /home/user/domains/ include(‘…’) #7 /home/user/domains/ plugin_sandbox_scrape() #8 {main} thrown in /home/user/domains/ on line 56

  • added AIOSEO > Note: AIOSEO will be discontinuing support for WordPress versions older than version 5.3 by the end of 2022.
  • Added Shield Security.
  • Created post + new category incl. featured image;
  • Update page, Created new page using MAKE builder
  • MAKE theme customizer still works fine.

Thanks for the feedback. I’m not sure what we can do with Classic SEO. I want the plugin to be active, but I’ve failed to get any developers on board to help maintain it.

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@Rudy_Brinkman about SEO I can confirm that CP SEO doesn’t work with 1.4 either. After extensive testing, I found Squirly SEO and it works fine with CP 1.5 and 1.4 without throwing errors.

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I understand - I’m not much of a developer so can’t be of any help in this :roll_eyes:

Can try this later in the day

PHP 8.1.13 (cli) (built: Nov 26 2022 14:07:36) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.13, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.13, Copyright (c), by Zend Technologies

Good install instructions for PHP 8

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If you have Ubuntu 20.04 LTS and are holding out on upgrading to Ubuntu 22.04, you might want to try upgrading to Ubuntu 22.04 instead of adding a PPA. Of course, if you have any packages that depend on Ubuntu 20.04 and will break on 22.04 (MongoDB being the one), then using a PPA should only be the last resort.

For me, I’m going to hold off until the developers of ClassicPress releases 1.5; however, so far I have not had any problems with Ubuntu 22.04 and PHP 8.1 for ClassicPress, even though ClassicPress developers only support PHP 8.0 and not 8.1.

For Classic Seo I have found a temporal workaround.


We have a new version of Classic SEO available for testing, it’s not released publicly yet. It has PHP 8 compatibility. Zip can be downloaded here.

We need to test it before it’s released.

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The link gives a 404-error.

Sorry about that, I didn’t notice release is still in draft status so it’s not public. You can directly download zip here.

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Made a backup and upgraded my production website at to the latest CP and upgraded the installed ClassicSeo by simply installing it replacing the existing install. Works perfectly fine. :+1:


Thanks. Great news.

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