Version 5.4 incompatible with caching?

Is it safe that multiple visitors use the same nonce because the same cached version of the page is served to them by the server?

Nonce is not a password, but what helps to verify that the request has surely come from your website, so supplying the same nonce to multiple visitors itself isn’t a problem.

I think most of caching products should have an ability to refresh cache on a regular basis. Why don’t you ask Cache Enabler’s support?

I am pretty familiar with Cache Enabler and there is nothing their support could do to change the situation. Cache Enabler supports two modes of operation:

• PHP mode: Every request to a page is directed to a PHP script that serves the page from the cache. If cache expiration is enabled, this script checks if the cached version is recent enough and refreshes the cache in case it’s too old.
• Advanced mode (faster, the configuration I am using): PHP is bypassed completely, pages from the cache are served directly by Apache (configured via .htaccess). No expiration check can be done in this mode of operation. The cache can be cleared via a cronjob, but as I described this is not a viable option.

I chose CF7 because it was compatible with the (fast) advanced mode and it would be great if it were compatible with this mode of operation in future too.