ReferenceError: React is not defined

Hi @natsshop,

Thank you for reaching out.

We are not really familiar with this error. Let us try to find the cause and a solution together. Lets begin at the start.

A) Is WordPress at it’s current version 5.4.1? If not, does the issue persists after updating?
B) Are all themes and plugins also up-to-date? If not, does the issue persists after updating?
C) Does your site meets the plugin requirements found here: https://yoast.com/help/plugin-requirements/?
D) If you deactivate Yoast SEO and delete the plugin. Then install & activate the plugin again from Plugins > Add New. Does the issue persists? We ask since there might be a missing or corrupt file that is causing this error.

If all of the above doesn’t help, we would encourage you to do a conflict check. This way you would test if the issue persists if Yoast SEO is the only active plugin using your current theme. If it still does, switch to a default twentytwenty theme and see if it still persists. It should not. When it then works, you know that your (child) theme is conflicting. If it works when Yoast SEO is the only plugin active with your theme, you can then enable 1 plugin at a time and check again until you find the culprit.

Hope this helps.

Hello,
Unfortunately no, I can’t get any further. That was of course the first thing I did. I’ve been looking for the error for 3 days now. That looks like a jquery error. Can it be that Yoast has problems with a WordPress jquery? No matter what I try, the problem remains. I also have a warning here that wordpress forced a layout display before the page was fully loaded. I used a common theme, all plugins disabled but the error is still. Also I was the only one who activated yoast, still there. I have been activating and deactivating plug-ins for days, but it is no different. I only activated Woocommerce and Yoast with a common theme. The problem is still there. I just have to say that now: I just don’t feel like the constant errors of WordPress and the PlugIns anymore. After every update there is always some problem! What else can it be?

@natsshop If the error is still persisting even with only the Yoast SEO plugin and a default theme such as TwentyNineteen active, we would recommend to check whether the error is being cached.

If you clear your cache (server, plugin/theme, browser, or CDN such as Cloudflare) does this resolve the issue? If you are not sure how to clear your server cache you should speak with your host provider. We have information on how to clear your browser cache at the following link: https://kb.yoast.com/kb/how-to-clear-my-browsers-cache/.

Hi,
unfortunately, no, that didn’t help either. Cache is completely empty, also on the server side. The Yoast Seo Contribution overview does not load on the dashboard start page. Here only the logo revolves around itself. Also the area “condition of the website” no longer loads. I think that’s a wordpress problem. I have already written to WP Support. No Yoast Seo Box is visible in the product description. Only the top bar. On the picture “yoast2” you see the description of Yoast on the right side. I’m waiting for what WordPress Support writes. But if you have any other ideas, please let me know. Thank you.
https://klon.nats-shop.com/wp-content/uploads/2020/05/yoast.jpg
https://klon.nats-shop.com/wp-content/uploads/2020/05/yoast1.jpg
https://klon.nats-shop.com/wp-content/uploads/2020/05/yoast2.jpg

• This reply was modified 4 years, 10 months ago by natsshop.

Unfortunately, we cannot see those images as they show a ‘This image was hotlinked’ image instead of the actual image.

ReferenceError: React is not defined

That really sounds like WordPress core is not working as react has been an included dependency since WordPress 5.0 (source). This could also mean that something has disabled or removed react but since you said you tested the issue with no active plugins and a default theme, that should have worked if core was working.

Using the built-in Site Health (Admin > Tools > Site Health), please click on the info tab and expand the ‘WordPress’ section. What version does the tool report for WordPress? If below 5.0, that is likely the reason.

If above 5.0, please install and activate the Health Check & Troubleshooting. Then go back to Admin > Tools > Site Health and click the ‘Tools’ tab and expand the ‘File Integrity’ secton. Click the button to run the check. If it reports that files have been changed in WordPress core, that would further lean towards an issue with core.

Please inform us of the results.

Hello, I did not understand the reference to the pictures. I can see the pictures when I click on the link.
Do you mean so?
https://klon.nats-shop.com/wp-content/uploads/2020/05/yoast3.jpg
What file is the core in? Then I reinstall that. Thank you for helping me with wordpress too. Unfortunately, nobody has yet contacted wordpress.
I’ve already tried the health check, but unfortunately it doesn’t work either. Also in the wordpress dashboard it only says here: The website condition is determined. But nothing comes. I haven’t followed your link yet, I’ll do that right away.
I have wordpress 5.4.1. I have already installed the Health Check & Troubleshooting plug-in, but that doesn’t respond and doesn’t show anything. I now follow your link and install another plug-in for the health check. There must still be other diagnostic plug-ins. Many thanks in advance for your help. I now also believe that it is due to WP. Woocommerce and WP also reports errors.
Yes, I already had the plug-in installed, but that doesn’t show any result either.

• This reply was modified 4 years, 10 months ago by natsshop.
• This reply was modified 4 years, 10 months ago by natsshop.

I have now followed your link source, but unfortunately that doesn’t tell me anything at all. I am a normal WordPress user and not a programmer.

Hi,
I have now set the debug mode in the wp-config and I get these warnings. I didn’t immediately come up with this idea because they said to me that these were not mistakes and that this was only important for developers.
I downloaded wordpress and the script-loader.php file both look the same. the one with me on the server and the one in the downloaded version. Can anyone do anything with the warnings here? What does “error when opening …” for recording mean … is there something wrong with the .php version of my host? The warning remains even if I switch to the wordpress backend.

Warning: include(/var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/assets/script-loader-packages.php): failed to open stream: No such file or directory in /var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/script-loader.php on line 238

Warning: include(/var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/assets/script-loader-packages.php): failed to open stream: No such file or directory in /var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/script-loader.php on line 238

Warning: include(): Failed opening ‘/var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/assets/script-loader-packages.php’ for inclusion (include_path=’.:/opt/plesk/php/7.2/share/pear’) in /var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/script-loader.php on line 238

Warning: Invalid argument supplied for foreach() in /var/www/vhosts/nats-shop.com/klon.nats-shop.com/wp-includes/script-loader.php on line 240

• This reply was modified 4 years, 10 months ago by natsshop.

Thank you for the many and quick answers, you don’t feel alone with the problem. But I found the solution: The Folder Assets with script-loader-packages.php was no longer there. I am still new on the current server and it is quite possible that I accidentally deleted it. There is no other explanation. I also accidentally deleted my theme recently because the checked files are not so well recognizable. Many thanks to everyone.

• This reply was modified 4 years, 10 months ago by natsshop.

Hi @natsshop,

Thank you for your replies and troubleshooting, happy to read you got it sorted.

Have a good weekend!. We’ll go ahead and mark this topic als resolved.

Thank you.