Wordpress LScache Plugin: LSCache serves webp images even to Firefox clients
Last Updated on: Wed, 15 Apr 2026 00:00:02 Hi, Weird things are happening on our website. LSCache is working very well, at least with Chrome? but with Firefox, it sometime serves webp images (that of course doesnt display properly on Firefox). On our homepage, 4 images are webp filetype according developer tools (even thought theyve got .jpeg extension). Image optimization was previously made using LSCache servers. I already did disable webp image replacement option, then check if option was removed from .htaccess, purge all files and then re-activate but no joy here. Shame because webp is doing a great job on Chrome? Anyone got an idea please? Thank you very much! The page I need help with: https://www.fdmjc-tarn.fr/ Hi @daffscat, currently our plugin will not detect if it is the browser support webp or not. Once the function turned ON it will replace all the image source which have .webp optimised. You can try to add a customise .htaccess to bypass webp for a specific browser. Hi @daffscat, I just checked your homepage with Firefox. I didnt see any webp image inside. As you can see the rewrite rule from .htaccess once you enabled webp replacement, it will check if the browser request header claimed that browser support webp or not, to decide if serve the webp to browser. For example, the current Firefox v67.0 I used shows Accept: text/html,application/xhtml+xml,application/xml q=0.9, / q=0.8 which doesnt have WebP, so lscwp wont serve WebP. Dear Hai and Stanley ! Thank you for your quick help and support! I had to re-import all images with this weird problem (jpeg extension on filename but actually webp image when looking with exif or metadata explorer) to make my homepage to work again properly. Didnt know what else to do and my boss was harassing me so? I thought it was working until I update a post and boom! This is a screen-shot of my Firefox Developer tools https://www.fdmjc-tarn.fr/wp-content/uploads/2019/08/lscache-webp-image-firefox-bug.jpeg You can see, each time it is a webp image, it won(t load in Firefox ans stay empty? Still dont know whats going on? maybe on the server side? Indeed Hai, I knew your plugin was able to make distinction (with htaccess rules or something else) between browser to serve webp image (or classic jpeg). Thank you for your help Can you kindly click on the main request for that page, and the webp requests, paste the request headers Accept here? Update: I can see Firefox did serve webp. Please give a report number of current status, without making any setting changes. Ok, maybe you will need to explain a little bit more but, if I understood correctly: Request headers: Host: http://www.fdmjc-tarn.fr User-Agent: Mozilla/5.0 (X11 Linux x86_64 rv:52.0) Gecko/20100101 Firefox/52.0 Accept: / Accept-Language: en-US,en q=0.5 Accept-Encoding: gzip, deflate, br Referer: https://www.fdmjc-tarn.fr/ DNT: 1 Connection: keep-alive If-Modified-Since: Wed, 07 Aug 2019 14:13:25 GMT If-None-Match: 4159-1565190878 Cache-Control: max-age=0 Response headers: Accept-Ranges: bytes Cache-Control: max-age=86400 Content-Type: image/webp Date: Wed, 07 Aug 2019 15:31:40 GMT Etag: 4159-1565190878 Expires: Thu, 08 Aug 2019 15:14:41 GMT Last-Modified: Wed, 07 Aug 2019 14:13:25 GMT Server: nginx/1.15.4 Vary: User-Agent X-Firefox-Spdy: h2 x-lsadc-cache: hit Is that what you want? Report number: IMZYHWWH Report date: 08/07/2019 15:35:11 Hi @daffscat, could you please join our Slack channel or submit a ticket here for helping us to reproduce the bug, thanks! Dear stanley @stanleylitespeed Ive just submit a ticket ( #557219 ). Finger crossed! Thank you very much for your help! Ill let you know. Best regards. For anyone who may be following this topic, we are still in the process of investigating the issue. Regards, -Michael
LiteCache Rush: Speed comes from using less, not from doing it faster
Reference