I recently moved this site to a new hosting provider. I made the change to improve the speed and thus the responsiveness of CompassionateGeek.com and our elearning courses. Shortly after completing the move, a few users complained about odd site errors. Among the errors, their progress wasn’t showing in their accounts, buttons were missing, and group accounts weren’t displaying newly purchased seats. These types of errors occasionally show up with elearning sites. They’re often caused by a browser cache and can be easily resolved by performing a hard refresh on the browser. That’s what I always recommend and it nearly always solves the problem. This time, however, it didn’t solve the problems. The behavior seemed like a cache issue, but I had already disabled the server cache, so I started looking at plugin conflicts on our server. I didn’t find any conflicts, but I did notice a new plugin that I hadn’t installed.
Our site runs LearnDash on WordPress on Debian Linux hosted by Cloudways. The hosting company, unbeknownst to us, installed two pieces of caching software (Breeze and Varnish). This is commonly done by hosting companies to improve performance. Normally, that’s a great idea. Not so for elearning software, which by its nature is very dynamic. Turns out that the surprise plugin was a second piece of caching software. It was the second one that caused the site errors for several of our users.
When I finally found the second one and disabled it, the site errors were resolved. I lost some hair in the process, but learned a lot!
The clue was when I went into BASH to manually delete the cache files (/wp-content/cache). The filenames were the same as the surprise plugin. I deleted the cache files and the problems went away. (You could also try the command wp cache flush while in your public_html directory.) I disabled the surprise plugin and so far, so good.
Although I wish hosting companies wouldn’t automatically install software like this, I understand why they do it and so far I’m pleased with Cloudways. One of the lessons I learned is to always audit server software installations when migrating to a new hosting company!
Thanks to everyone for your patience during this process.