Working on this site with the new WP v5.8.2 I was hitting an error when using block editor.

I installed the ‘Classic Editor’ plugin so that I could keep working…
The data in the error looked like this…
Nc@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:72:66
@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:81:435
T@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:95:474
zj@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:230:157
Th@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:152:225
tj@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:152:154
Te@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:146:153
Te@[native code]
@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:61:69
unstable_runWithPriority@https://www.blandford.tech/wp-includes/js/dist/vendor/react.min.js?ver=16.13.1:25:261
Pg@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:61:16
ha@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:60:453
Ja@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:224:402
ch@https://www.blandford.tech/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.13.1:93:81
ch@[native code]
e@https://www.blandford.tech/wp-includes/js/dist/data.min.js?ver=a9e98fe3ad76884fe7909ba8348395b7:2:20892
t@https://www.blandford.tech/wp-includes/js/dist/data.min.js?ver=a9e98fe3ad76884fe7909ba8348395b7:2:20959
@https://www.blandford.tech/wp-includes/js/dist/data.min.js?ver=a9e98fe3ad76884fe7909ba8348395b7:2:15083
b@https://www.blandford.tech/wp-includes/js/dist/data.min.js?ver=a9e98fe3ad76884fe7909ba8348395b7:2:8589
@https://www.blandford.tech/wp-includes/js/dist/redux-routine.min.js?ver=fd5f93d1f8206c65d1891cf1f898211e:2:1354
some@[native code]
r@https://www.blandford.tech/wp-includes/js/dist/redux-routine.min.js?ver=fd5f93d1f8206c65d1891cf1f898211e:2:9237
@https://www.blandford.tech/wp-includes/js/dist/redux-routine.min.js?ver=fd5f93d1f8206c65d1891cf1f898211e:2:9187
promiseReactionJob@[native code]
Site Health (plugin) was giving me this…

Solution
I was able to get everything working by making sure that my Nginx site config contained the following:
location / {
try_files $uri $uri/ /index.php?$args;
}
You have to include the "?$args" part so non-default permalinks doesn't break when using query string
Lastly don’t forget to restart Nginx so that the changes are applied.
I hope this helps someone, since I wasted a couple hours getting to the bottom of this. 🙂
