I did not save the configure options I used when I compiled the ftp server back in 2012 on the last incarnation of our ftp and web server. Consequently I had to guess at some of them.
One bad guess was –paranoid, which said, “Disable some questionable features”. It turns out two of those features was the ability to remove or overwrite a file.
This broke a number of weather stations and the ability for one person to update his website.
I have removed that option which seems to have resolved these problems.