RedisException: read error on connection in object-cache.php:1133

Hi,

We have an website were we using the Redis, WP-rocket and UserPro plugins on our WordPress website. At random moments we are seeing this in our error logs. The stack trace can be found below:

[22-Apr-2020 13:54:25 UTC] RedisException: read error on connection in wp-content/object-cache.php:1133
Stack trace:
#0 /wp-content/object-cache.php(1133): Redis->set(‘wp:options:allo…’, ‘a:1234:{s:7:”si…’)
#1 /wp-content/object-cache.php(229): WP_Object_Cache->set(‘alloptions’, Array, ‘options’, 0)
#2 /wp-includes/option.php(406): wp_cache_set(‘alloptions’, Array, ‘options’)
#3 /wp-includes/class-wp-rewrite.php(1469): update_option(‘rewrite_rules’, Array)
#4 /wp-includes/class-wp-rewrite.php(1805): WP_Rewrite->wp_rewrite_rules()
#5 /wp-includes/class-wp-hook.php(288): WP_Rewrite->flush_rules(true)
#6 /wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters(NULL, Array)
#7 /wp-includes/plugin.php(478): WP_Hook->do_action(Array)
#8 /wp-settings.php(545): do_action(‘wp_loaded’)
#9 /wp-config.php(57): require_once(‘/var/www/vhosts…’)
#10 /wp-load.php(37): require_once(‘/var/www/vhosts…’)
#11 /wp-blog-header.php(13): require_once(‘/var/www/vhosts…’)
#12 /index.php(17): require(‘/var/www/vhosts…’)

After this stack trace we see that the PHP-FPM processes and the Database connections reaches their max which is resulting that the webserver becomes unavailable.

Any help or solution on how to tackle this will be greatly appreciated.

Thanks in advance.