forum.freeciv.org

I play with 2.4.3 and at the very beginging, I have found one of my citys stoped production, it means it didn't want to produce anything. How to solve it?

We'd need more description, preferably screencaps, to know what you're talking about. At least, I have no idea.

First, it said that some barbarians were near the city, then 3 to 5 turns the city didn't produce anything. After that, it restarted to produce.

Maybe barbarians displaced one worker from a tile with some shield production to a tile with none. Or maybe you finished new unit that took the last shield / turn production as maintenance cost. Then city could have grown to gain another worker, or workers moved back to their places for some other reason.