Issue with expired fbclid value in fbc parameter

Hello, I’m using Pixel Cat (free version) with Conversions API integration. Everything works fine, but I’m getting this warning in Meta Events Manager: “Your server is sending an expired fbclid value in the fbc parameter.” We haven’t modified the fbclid or _fbc manually — everything is handled through the plugin. Can you please check if this issue comes from the plugin itself or if there’s anything I need to configure differently? Thanks in advance. Best regards, Mohammad – Gishar Tapetes The page I need help with: [ log in to see the link] Hi Mohammad, Thanks for your patience while I looked into this. I ran some tests using your site and found that the issue is likely caused by WP Rocket’s page caching. When visiting a URL like this: https://gishartapetes.com/?fbclid=testvalue456 …the page is served from WP Rocket’s cache. Because the page was likely cached before the fbclid parameter was present, the Pixel Cat plugin never sees the new fbclid — and therefore doesn’t update the _fbc cookie. That’s why Meta is flagging the value as “expired”. However, when we visit: https://gishartapetes.com/?nowprocket&fbclid=testvalue456 …the cache is bypassed (thanks to the ?nowprocket parameter), and everything works correctly: the new fbclid is picked up, and _fbc is updated. What to do: To avoid this issue going forward, we recommend one of the following: Exclude landing pages from WP Rocket cache , especially if they’re used for ads (and receive fbclid parameters). Disable cache for URLs with query parameters , or at least for fbclid if possible. This will allow Pixel Cat to update the _fbc cookie reliably, keeping Meta’s Conversions API integration working smoothly. Let us know if you’d like help configuring this or if anything’s unclear. All the best. Hi Pixel Cat Support Team, Thank you for your previous detailed explanation regarding the fbclid modification error and the recommended solutions for WP Rocket. I have followed your instructions carefully: I have added both _fbc and _fbp to the “Never Cache Cookies” section in WP Rocket. I have also added (.*)\?fbclid=(.*) to the “Never Cache URLs” section in WP Rocket to ensure that pages with fbclid parameters are not cached. After making these changes, I performed a full cache clear on WP Rocket, Cloudflare (if applicable), and my browser. I also closed and reopened the browser before testing. However, after running new test purchases in Meta Events Manager, the fbcid modification error ( “Servidor enviando um valor de fbcid modificado no parâmetro fbc” ) is still appearing in the “Diagnóstico” tab. Could you please advise on what further steps I can take to resolve this issue? It seems the caching exclusion is not fully preventing the fbcid modification. Thank you for your continued support. Best regards, [/Mohammad] Gishar Tapetes Hi Mohammad, Thanks for the update and for trying those exclusions. I understand how frustrating it must be that the error is still appearing. Since the URL and cookie exclusions haven’t fully resolved it, let’s try excluding the plugin’s own files from being cached. Could you please try excluding the entire Pixel Cat plugin folder from being cached by WP Rocket? You’ll typically add its path to WP Rocket’s “Never Cache URLs” or a similar exclusion setting. The path should look something like: wp-content/plugins/pixel-cat/ (or whatever the exact folder name for Pixel Cat is on your site, if it’s different). After adding this, please clear all caches again (WP Rocket, Cloudflare, and your browser) and then re-test. If that doesn’t work, I recommend checking in with WP Rocket for assistance on this, I wouldn’t be super up to date on their exclusion feature. Let me know how that goes. All the best. Hi Pixel Cat Support Team, Thank you again for your previous help. I’ve continued troubleshooting the issue with the modified fbc parameter on server-side events. Here’s what I’ve confirmed so far: The _fbc cookie is now correctly created in the browser using a valid fbclid . I verified this by visiting my site with a test fbclid (e.g. test987 ), and the _fbc cookie stores the full correct value: fb.1.timestamp.test987 . Browser-based events (like PageView and InitiateCheckout ) are processed correctly in Events Manager. However, server-side events (via CAPI) still trigger the “modified fbc” diagnostic error in Meta. This suggests that the Pixel Cat plugin may be sending a cached or fallback fbc value during CAPI events, instead of the updated one stored in the browser. I only have Pixel Cat installed (no other tracking plugins), and I have already excluded the plugin folder from WP Rocket’s cache and cleared all cache layers. Could you please investigate why the server-side events are not using the latest _fbc value? And is there any way I can force the plugin to always use the current cookie value from the browser for fbc when sending CAPI events? I’m happy to provide additional screenshots or logs if needed. Best regards, Mohammad – Gishar Tapetes Hi Mohammad, I hope you had a good weekend. Thanks for the continued updates and your patience as we investigate this fbc discrepancy. In your initial message, you mentioned using the Pixel Cat (free version). Could you please confirm which version of Pixel Cat you are currently using on your site? This information is important for our troubleshooting, as different versions of the plugin have different features (like Advanced Matching) that can impact the CAPI integration and how the fbc parameter is handled. Thanks again for your help. All the best.