Wordpress and PHP8

[UKSBD]

Is anyone else having problems with Wordpress and PHP 8?

I've just done a fresh set up on a new domain

Set everything up using PHP 7.4, then once set up and working changed to PHP 8

The site works using 8 but it automatically logs me out of control panel and when trying to login get the message

"Error: the username *** is not registered on this site. If you are unsure of your username, try your email address instead."

Switch back to 7.4 and all is OK again

Fresh install using default theme and no plugins (apart from the 2 that come with fresh install)

 

[Solve My Problem]

I haven't had any issue with it on PHP8 on dev platforms, although it's still not running on most production at the moment.

Where are you running it? locally or a hosted environment

Darren

 

[UKSBD]

I haven't had any issue with it on PHP8 on dev platforms, although it's still not running on most production at the moment.

Where are you running it? locally or a hosted environment

Darren

Just set it up on a live site which I'm currently setting up

 

[Solve My Problem]

Checked the server logs? Enable PHP logging and see if anything obvious comes up

Darren

 

[Solve My Problem]

WordPress 5.9 and PHP 8.0-8.1

PHP 8.1 was released on 25 November 2021. PHP 8.1 contains new features, performance improvements, deprecations, and backward compatibility breaks. For more information, see the PHP 8.1 release pag…

make.wordpress.org

 

[UKSBD]

I'm just going to leave it at 7.4 until it's more stable

 

[fisicx]

It’s all good with PHP8 here (over 20 live sites with all sorts of themes and plugins). Able to login on all of them.

This feels more like a server issue than it does Wordpress. Login is not dependent on any php8 functionality.

 

[James (iimttd)]

We had some issues a while back with PHP8, from memory there was an issue with MySQLi(?).

Are you using any plugins that handle user registration/login/redirects, etc? One client has had a site botched by plugins like this (not our doing, thankfully).

Lastly, a desperate but possible thing is resetting the salts just incase of any odd caching?

 

[UKSBD]

We had some issues a while back with PHP8, from memory there was an issue with MySQLi(?).

Are you using any plugins that handle user registration/login/redirects, etc? One client has had a site botched by plugins like this (not our doing, thankfully).

Lastly, a desperate but possible thing is resetting the salts just incase of any odd caching?

It was a fresh install with no plugins and using the default theme.

It's now got a couple of plugins (classic editor, classic widgets) and a bespoke theme and functions.php

Still not working in PHP 8.00 but I tried it on 8:1 and appears to be fine.

Not going to update any existing sites yet, just use this one for testing.

 

[fisicx]

You need to look at error.log or enable wp_debug. This will tell you what is causing the error.

 

[UKSBD]

You need to look at error.log or enable wp_debug. This will tell you what is causing the error.

I couldn't be bothered.
I dare say the host will sort it all out before 7.4 is unsupported

 

[SEODEV#338055]

Yes some Wordpress plugins are not compatible with PHP8 and may break your websites, although plugin creators were asked in Nov 2020 to make sure plugins became compatible with PHP8

"All plugin and theme developers, as well as hosting communities, are called on to make their code compatible with PHP 8." (Nov 2020, Wordpress.org)

WordPress and PHP 8.0

Update on November 24, 2020: Added a call out in the “Strict type/value validations for internal functions” section that there are still scenarios where WP Core could potentially pass i…

make.wordpress.org

Best answer is to deactivate all non essential Wordpress plugins before upgrading to PHP8

Make sure only PHP8 compatible plugins are being used on your build

I think PHP8 is a mandatory upgrade as support for PHP7.4 will end in 9 months on 28 Nov 2022

PHP: Supported Versions

PHP is a popular general-purpose scripting language that powers everything from your blog to the most popular websites in the world.

www.php.net

Obviously back everything up before you upgrade PHP

 

[HostXNow]

It’s all good with PHP8 here (over 20 live sites with all sorts of themes and plugins). Able to login on all of them.

This feels more like a server issue than it does Wordpress. Login is not dependent on any php8 functionality.

No issues here. I agree it is an account/server issue -- which web hosting control panel are you using?

Be sure to check .htaccess and .usr.ini and php.ini (if any) to make sure there is no conflicting PHP7/8.

 

[SEODEV#338055]

Safe to upgrade to PHP8

Best to check each plugin support site first

You can email the support and ask if PHP8 is compatible with each plugin

Time consuming but worthwhile

 

[fisicx]

Safe to upgrade to PHP8

Best to check each plugin support site first

You can email the support and ask if PHP8 is compatible with each plugin

Time consuming but worthwhile

If you read his post it’s a clean install. There are no plugins. The issue is the login screen which is doesn’t use any php8 functions.

 

[UKSBD]

It wasn't just the login

Once switching to 8 I was getting 503 errors

I found the problem though

For some reason my host hasn't got the mysqli extension available with PHP 8 they have mysqlnd instead.

If I switch back to 7.4 or switch to 8.1 mysqli is available again and both work

 

[UKSBD]

We had some issues a while back with PHP8, from memory there was an issue with MySQLi(?).

Yes, it looks like that was the problem, my host hasn't got the MySQLi extension included with PHP 8.

It's included with 7.4 and with 8.1, no idea why they haven't included it with 8 though, they just have mysqlnd instead

 

[SEODEV#338055]

Thanks for the update

It's probably off topic but I have had a lot of challenges with PHP8 and Wordpress

Starting a new thread