When I began this site a few months ago to replace the old one, I began using the NextGen Gallery plug-in for WordPress. My main activity is on the home site so I did not notice the problems with NextGen. Essentially, it appears that the developer introduced a major update, which does not work on this installation. Therefore I will have to remove it.
This is going to add much more work to my task list at a time when I really do not need it, but I will address it. I am very annoyed at the developers of NextGen, and strongly advise people not to use it. Setting up photography sites is a nightmare to begin with and we do not need buggy, untested software to complicate matters. It is not acceptable for plugin developers to tell users to remove other plugins or even change their site themes– just to get their updates to work.
On the upside, WordPress’ own JetPack suite now has much of the functionality that made NextGen interesting. I will be moving to that, since at least there is some hope that it will not suddenly stop working!