[@davidanderson Participant 12 years, 2 months ago]

Hi Stephen,

Thanks for getting back. Too right that it’s weird! It’s definitely not a browser or CloudFlare or WP Super Cache cache issue – that was what I was investigating when I posted the Apache logs. You can see that successive log entries deliver different numbers of bytes, e.g.:

1.2.3.4 - - [12/Aug/2014:20:02:36 -0400] "GET /forums/topic/updraft-migration-issue/ HTTP/1.1" 200 74091
1.2.3.4 - - [12/Aug/2014:20:03:48 -0400] "GET /forums/topic/updraft-migration-issue/ HTTP/1.1" 200 39159

74091 bytes corresponds to a page load when the forum appeared; 39159 corresponds to that portion being blank (when I hit “reload”, 10 seconds later). It goes back and forth like that with no apparent pattern – you can’t predict what’s next.

Just to make sure I also tested with WP Super Cache deactivated (it had nothing in wp-content/cache for these pages anyway), and CloudFlare in developer (no cacheing) mode, and emptied the CloudFlare cache.

Also, when the forum is produced by a shortcode, it works 100% of the time. No other pages on the site do this, or ever have done. The previous forum plugin (Mingle Forum) is both de-activated and removed, so it’s not that interfering.

So, it seems certain to me that it’s something to do with permalink hierarchy.

Any suggestions how I can debug this? I have 100% access to everything. But, I’m more of a back-end developer – stuff to do with permalinks and custom post types is stuff I’ve only dabbled in, and I’m not sure where to start diving in. It’s easily reproducible (just keep hitting reload enough times, and the behaviour will change).

David