Database error after latest ubuntu updates

where do you get the error? May I see a screenshot of the error please?

On server error.logs
A second problem I found, which is in corelation:I was forced to disable WPFC module, cause it is generating problems with IQ block country modules. It is not blocking countries anymore. I need to use IQ block module for to sort content of my site to different countries and in this case I prefer to have no extra cache on page, before the whole world can see whole content of my WP-site.

ADD: the refer URL of the error is related to cron. So when cron is made than it writes this error each time:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘) AND ((cd_posts.post_status = ‘publish’)) ORDER BY cd_posts.ID DESC LIMIT 0, 3′ at line 1 f\xc3\xbcr Abfrage SELECT SQL_CALC_FOUND_ROWS cd_posts.ID FROM cd_posts WHERE 1=1 AND () AND ((cd_posts.post_status = ‘publish’)) ORDER BY cd_posts.ID DESC LIMIT 0, 3 von do_action_ref_array(‘wp_fastest_cache_Preload’), WP_Hook->do_action, WP_Hook->apply_filters, WpFastestCache->create_preload_cache, PreloadWPFC::create_preload_cache, referer: https://xxxxxxx/wp-cron.php?doing_wp_cron=xxxxxxxxxxxxxxx

you can disable preload option then.

I fixed the problem. You need to delete WP Fastest Cache and download the following version to get the latest changes.

https://downloads.www.ads-software.com/plugin/wp-fastest-cache.zip