This is happening when I am in the command window of freeciv server and type "save <generic filename>"
This how the server responds:
1: In file Europe-T0250a.sav.bz2, there is no entry in the registry for
event_cache.events174.timestamp (or the entries are out of order). This means
a less efficient non-tabular format will be used.
To avoid this make sure all rows of a table are
filled out with an entry for every column.
1: Please report this message at....
After a year of being away from the game (on 2.5.11), I decide to download 2.6.0 I copied the most recent bz2 file from the old raspberry pi 3 onto a new fully patched raspberry pi 4 running raspian OS. Unfortunately, Raspian OS doesn't have anything more recent.
So I can open the 2.5.11 bz2 file using 2.6.0 server, and then from two other machines connect to it using GTK client 2.6.0. The game looks playable so I played some. I then went back to the server, and told it to save to a new file. That's when I got the message.
I also received the error message minutes later. I shut down both clients, shut down the server, then restarted the freeciv server, loaded the recently saved game, and immediately saved it. I received the same error message.