Failed to load resource: net::ERR_HTTP2_PROTOCOL_ERROR

Hi @utnalove,

it looks like you might have some issues with the sever configuration of HTTP2… All the assets/resources are not loading correctly.

I would suggest that you contact your hosting support for help on this issue, since probably similar issues occur for other plugins/assets?

Take care!

Hello,

I took some time to reply, because we were analyzing it.
Http2 is well on and it seems to work fine.

In wp-admin in the screens of other plugins, there are no errors related to other plugins.
The only errors are related to wp-mail-smtp.

For example everywhere I can see such error.

This file cannot be downloaded by the browser.

At the same time in the access.log there is a 444 error:

theipaddress - - www.example.com [08/Oct/2020:10:38:22 +0200] "GET /wp-content/pluginpath/wp-mail-smtp/assets/css/admin-bar.min.css?ver=2.4.0 HTTP/2.0" 444 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36" "-"

Hi @utnalove,

hmm… this is strange.

Our plugin’s assets (CSS and JS files) are not anything special, so I’m not sure why only these files are causing you issues?

The status code 444: https://httpstatuses.com/444:

> …close the connection without sending a response to the client, most commonly used to deny malicious or malformed requests.

I don’t have any HTTP 444 error experience and there were no other reports of these kind of errors. I still believe your server configuration is marking these files for whatever reason and they are prevented from being loaded…

I’m sorry I can’t be of more help.

Take care!

thank you for your help!
After searching and searching I found the root cause:

This rule in nginx:

location ~* (roundcube|webdav|smtp|http\:|soap|w00tw00t)
{
        return 444;
}

Hi @utnalove,

I’m glad you found the source of this issue.

Thank you for sharing this with others, so they can check for this if they experience the same issue.

Have a nice day!