Apologies, my bad, looking better at your screenshot (and at the numerous post that you have made) it seems that you have completely destroyed the file name template

Fortunately it seems that other users have already brought you on the right track

Anyway, the default file name template is "%n_%f_%p.%e", where:
- %n is the name of the render target node,
%f is the frame number,
%p is the render pass name,
%e is the extention of the image file saved,
you can also add:
- %i render target index number,
%t time of the rendered image in h_m_s,
Please, next time avoid cross posting, it's hard to track your request and could be confusing for other new users, thanks

ciao beppe