Hi @florentmerlat
Do you see this error on the backend (at your admin area) or on your frontend (what your visitors see)?
If it’s a frontend error, do you use any kind of caching/optimization plugin on your site?
Usually these plugins disable themselves when you put a query string to the URL, so you could try to visit the page like this:
https://yoursite.com/?test=1
and see if the error is present like that.
If all is well, probably the optimization plugin tries to modify the JavaScript code loading order and that causes the issue.
We’ve seen this error caused by WP Rocket’s “Delay JavaScript execution” option. If you’d have WP Rocket, you could try to go to WordPress > Settings > WP Rocket > File Optimization and there should be an exclude option below the Deleay JavaScript execution option. You could try excluding our codes by writing the following to a new line:
_nslDOMReady
and that should solve the problem.