Regenerate not working – Server Configuration Error

Hi @captainproton,

Thanks for your message.

Please read the error message again. It is impossible to better explain the issue. The message contains all the information to present the problem.

Unfortunately, I am not able to help you any more. This is a problem with your server configuration. The plugin detects such problems and informs the user about it.

Please contact your server administrator.

If you have this problem now, it means that it was occurring all the time, but you were not aware that something was not working properly.

Is there a valid reason why the “Regenerate” button is disabled when this error is shown. It seems when the error is bypassed regeneration works perfectly, the site works perfectly and all redirects work as expected.

Even with no form of caching the error continues. All http headers suggested everything is fresh with no-cache. Server response also says no-cache.

I’d be interested to know what error is being picked up that no other plugin or site, using wordpress, joomla, html, can detect.

I’m sorry if my attitude appears a little off but I’m trying to understand what the problem really is.

Thanks for you help.

@captainproton, please contact me via e-mail – mateusz[at@]gbiorczyk[dot.]pl. I will try to diagnose your problem individually.

I also facing the same issue.

Server configuration error

Your server uses the cache for redirects. The rules from .htaccess file or from Nginx configuration are not executed every time when the image is loaded, but the last redirect from cache is performed. With each request to image, your server should execute the rules from .htaccess file or from Nginx configuration. Now it only does this the first time and then uses cache. This means that if your server redirected image to WebP format the first time, it does so on every request. It should check the rules from .htaccess file or from Nginx configuration each time during request to image and redirect only when the conditions are met. Disable server cache for redirects. Please contact your server administrator.

Regenerate Button Disabled

@mateuszgbiorczyk Thanks for you reply and again I apologise if my previous reply wasn’t respectful at all.

I also bypassed the Nginx Reverse Proxy and went straight to Apache and the same issue continues. All .htaccess files are correct as far as I can tell.

I have temporarily resolved the issue by bypassing the code which throws this particular error. I’ve done this for all my sites.

The ‘Regenerate’ button is re-enabled and works perfectly. I have tested all sites with and without caching with no issues.

Given that this error message appears minor then perhaps an option to ignore it rather than if effectively being fatal. By fatal I mean we cannot regenerate.

I will email you directly in the next day or so.

Other than the issue I’m having I consider it to be an excellent plugin and it works as advertised. ??

Same problem. Rather urgent for me

@captainproton Can you provide what you snipped please?

@captainproton, @awkath and @deepvoice What is your Nginx configuration for the plugin? Can you pass her on? Is it the same as the FAQ??

@deepvoice Sorry for not getting back to you. I’ve been out of town.

I modified /wp-content/plugins/webp-converter-for-media/app/Settings/Errors.php

Around line 79 I commented out the following;

} else if ($this->ifRedirectsAreCached() === true) {
        $errors[] = 'rewrites_cached';
      } 

It now looks like this;

} /** else if ($this->ifRedirectsAreCached() === true) {
        $errors[] = 'rewrites_cached';
      } **/

I should point out that bypassing error checking is never a good idea and this is a temporary fix allowing you to regenerate.

@mateuszgbiorczyk Sorry, I’ve been out of town. I will send a copy of my Nginx config when I get home later. Sorry to hold you up.

@mateuszgbiorczyk

I have resolved the issue by adding the following;

# Don't cache Webp

      if ($request_uri ~* "/*.webp") {
        set $do_not_cache 1;
        set $skip_reason "WEBP";
        set $bypass 1;
        }

My Nginx and Apache were exactly as the FAQ suggested, including .htaccess.

I did need to make one minor change with the try_files within the server block.

try_files /wp-content/uploads-webpc/$path.$ext.webp $uri =404;

became 

proxy_pass https://apache_backend;

I have a few physical server boxes here. Nginx is machine with apache on another. Nginx is used only for caching apache.

The problem I have with bypassing the cache is the passing requests for images back to apache all the time rather than Nginx caching them. All sites are cached in a ram-drive. The apache machine processes php and other stuff and Nginx holds it all in memory. There is no disk activity at all when serving pages & images. So, bypassing caching for webp is a bit of a problem.

@captainproton, that’s great information. I am very happy. Tell me please, does this apply only to your server or can it apply to others?

What can I do to help other users in the future?

Hey there @mateuszgbiorczyk

Thanks for your help.

Not sure if this would apply to others or not. Perhaps it would if they have Nginx as a reverse proxy to an Apache back end.

My configuration is based on many examples of Nginx reverse proxy techniques. The major difference is all pages are served out of ram rather than on disk.

In case it is useful for others, below is the entire wordpress.conf which I include for my WordPress sites. Don’t take this as the perfect setup because it could do with improvement. It’s an ongoing thing.

# CACHE CONFIGURATION for WordPress

# define nginx variables

	set $do_not_cache 0;
	set $skip_reason "";
	set $bypass 0;
  
# Don't cache URIs containing the following segments

	if ($request_uri ~* "/wp-admin/|/xmlrpc.php|wp-.*.php|/feed/|sitemap(_index)?.xml|wp-cron") {
	set $do_not_cache 1;
	set $skip_reason URI;
	set $bypass 1; 
	}

# Don't cache people signing up

	if ($request_uri ~* "/join/|/wp-login.php?action=register|/wp-login.php?") {
	set $do_not_cache 1;
	set $skip_reason URI;
	set $bypass 1;
	}

	if ($request_method = POST) {
	set $do_not_cache 1;
	set $skip_reason "POST";
	set $bypass 1;
	}   

# skip caching WordPress cookies

	if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wordpress_(?!test_cookie)|wp-postpass|wordpress_no_cache|wordpress_logged_in") {
	set $do_not_cache 1;
	set $skip_reason "Cookie Type";
	set $bypass 1;
	}
  
# Don't cache URIs for wordpress preview

	if ($request_uri ~* "preview=true") {
	set $do_not_cache 1;
	set $skip_reason "PREVIEW";
	set $bypass 1;
	}

# Don't cache Webp

      if ($request_uri ~* "/*.webp") {
        set $do_not_cache 1;
        set $skip_reason "WEBP";
        set $bypass 1;
        }

# CACHE CONFIGURATION for WordPress - END

@captainproton, this part solves the cache problem? Does it work for all servers or are the variables $do_not_cache, $skip_reason, and $bypass individual for you?

if ($request_uri ~* "/*.webp") {
  set $do_not_cache 1;
  set $skip_reason "WEBP";
  set $bypass 1;
}

Thank you very much for your commitment.

@mateuszgbiorczyk Yes, the $do_not_cache, $skip_reason and $bypass are variables. $skip_reason is nothing more than a string used in response headers and isn’t required.

I originally (12 months ago) set up my servers loosely based on this tutorial; https://www.ryadel.com/en/nginx-reverse-proxy-cache-wordpress-apache-iis/

When those variables set to 0 the request is retrieved from cache, when set to 1 it is served by Apache.

It will only work for servers using Nginx as a reverse proxy. If they are using Nginx as their main http server then it would probably fail. I’m not an expert and really can’t offer a firm solution, but it worked for me.

Also, bypassing the cache to serve images defeats the purpose of a cache and impacts performance. For me this is a temporary workaround.