Until a month ago, I had been delighted with the service I had been getting from the macOS Content Caching server. It effectively enabled me to download single updates to Xcode from the App Store, then install those at lightning speed on each of my other Macs. Syncing with iCloud Drive had also become far more reliable, and Macs seldom sat there with their progress circle not quite full. Security updates had also worked perfectly, as with macOS updates. Managing four Macs had become so much quicker and simpler.

With the routine XProtect update to version 2160 on 9 June, this all started to go wrong, to the point where I ended up filing a Feedback with Apple. It turned out that the Content Caching server was at fault: the update it had downloaded from Apple’s servers wouldn’t install correctly. In the end, I turned the caching server off and updated each Mac without its interference. Once they were done, I turned it back on, but didn’t flush its cache.

By 17 June, when Apple shipped the next update to XProtect Remediator, I was ready. After the first failed install, I turned the caching server off, and each Mac updated without any further trouble. The same happened on 30 June with XProtect Remediator 64 and XProtect 2161, and again last night with XProtect Remediator 65.

In between those updates, it works just as well as ever. At one stage, when it was giving me trouble, I flushed the server’s cache, kissing goodbye to around 100 GB of cached updates in the process, but the next time I tried to download and install that update the same failure occurred.

From where I’m sitting, I can’t understand what has happened to disrupt this previously reliable service. But every time one of my Macs asks for a security data update, such as XProtect or XProtect Remediator, it’s provided with a copy which can’t install on any of the client Macs. Yet when those clients ask Apple’s software update servers for the same updates, they install fine.

I’m aware that I’m not the only one who is continuing to have these problems with the Content Caching server. I’d be very grateful if you could comment here if you’ve experienced similar difficulties with failed updates since early June, particularly if you’re running a local Content Caching server. I’d be even more interested to hear from you if you’ve had these problems and managed to resolve them.

If you want further help on what to do to deal with problems updating, this article is a good start.