Load more posts button sometimes doesn’t work

Just noticed this is happening to megamenus as well, maybe it’s related to Ajax support? I’ve recorded a quick video: https://d.pr/v/iCJxBj

It seems like the conflict is with WP Rocket, our caching plugin.

I’ve opened a ticket with them, but if you could also test it on your side…

It’s very weird. Following their advice, I’ve disabled all WP Rocket’s built-in optimization/caching features and it still doesn’t work fine — only if I really deactivate the whole plugin.

(I’ve posted a reply here, yet another one sent to spam. Please approve it.)

I’ve been working with the WP Rocket guys, but we still haven’t found the cause of the issue.

I found this possible related error log:

[12-Jul-2019 14:34:06 UTC] Database error from WordPress Deadlock found when trying to get lock; try restarting transaction para a consulta DELETE FROM wp_options WHERE option_name = ‘_transient_newsbeat_child_dynamic_css_vars’ feita por require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/newsbeat-child/404.php’), get_header, locate_template, load_template, require_once(‘/themes/newsbeat/header-404.php’), wp_head, do_action(‘wp_head’), WP_Hook->do_action, WP_Hook->apply_filters, wp_enqueue_scripts, do_action(‘wp_enqueue_scripts’), WP_Hook->do_action, WP_Hook->apply_filters, wpthmsNewsbeat\Addon\AnimationsAndEffects\Plugin->wp_enqueue_script, wpthmsNewsbeat\Addon\AnimationsAndEffects\Plugin::style, newsbeat__get_css_vars, delete_transient, delete_option

And they last replied this:

I’ve checked what request is being sent through ‘Load more’ button, please take a look at it:
https://jmp.sh/WlmdTdX
https://jmp.sh/P0cMuEe

I believe that security and nonce might be the problem. For example, the security value changes each hour, and it needs to be correct in order to proceed with this request. Imagine that your page is cached for 2 hours and site is sending request with outdated security value. It could respond with that kind of error.

I would definitely ask the author of this load more script about that value and compatibility with full page cache solutions. For testing purposes, I’d decrease Cache Lifetime (in the Cache section) to 1 hour and see if it helped. If so, extend it to 2 or 3 hours, check and so on.

Please let me know if that makes sense to you.

I’ve since set WP Rocket’s cache to last 1 hour, but the issue is ongoing and intermittent.

That’s, will try that. Setting it for a week is bad for security?

Well it hasn’t solved the issue yet, and the worst part is that it’s very intermittent. It’s not working for me right now, it might work again in 5 minutes.

I’m not even sure WP Rocket has anything to do with it, at all…

But I’ve changed it to last a whole week and cleared the whole site’s cache… if that didn’t fix the issue, then it’s not the nonces. Right?

It doesn’t make any sense to cache dynamic pages for so long. I currently have it set for 1 hour.

Why would a new page cache conflict with nonces? Shouldn’t it use the current generated nonce?

That’s why I set the cache to only last an hour, that way we know it’s not using an old nonce.

This is still not working as it should, it’s driving me mad.

Do all Ajax requests need that nonce code? Do you really think that’s the issue here?

Understood. I just don’t think the issue with WP Rocket might be related to that, then…

So I thought the other issue we had with the Insert Post Ads plugin might have been related to this one, but it is not.

I’ve just turned off WP Rocket again so Ajax requests can work.

This is still an issue for me.

Here’s the Console error when I click to load more: https://d.pr/i/uCtYua

Does that help, Jacob?

I’m sorry but that reply didn’t help much, Jacob. Why would my server block an AJAX request? And why would it work if I refresh the page a few times and try it again? If the server is indeed blocking it, how do I fix it? Is it an issue with my server or with the theme’s code?

Still doesn’t help fix the issue. Should we increase that nonce expiration? Is that possible? If so, how do I do that?

It simply doesn’t work for me 90% of the times.

I really don’t think WP Rocket is the issue here, I have its cache lifespan set to only 4 hours as they recommend there.

On my first try after disabling HTML minification, it already didn’t work. So it’s not that either.

I don’t see any new errors in WordPress’ log when clicking the “load more” button.

And yes Jacob, it didn’t work on my normal window but it did in incognito mode. I just don’t understand what does that mean; can I fix it in all cases?

I don’t think it has to do with the browser’s cache either, Jacob, as I usually refresh the page holding Shift + Option to make sure the cache is cleared.

What I’m thinking now is that our site is externally cached by a proxy server, and as I’m always logged to our WordPress Admin, maybe my security nonce will always be different than the site’s public/cached one? Does that make any sense?

I’ve searched for issues related to that and it still seems to be related to WordPress’ security nonces. I’ve decreased WP Rocket’s cache lifetime from 8 to just 1 hour now, let’s see how it goes.