Hi,

If in the admin panel > Listing > Listing Settings > Optional fields > Price and Attach images are unticked on the new item_add I have error:
- the price section no longer appears on the page
- I can no longer add images and the page crashes I can't go forward or back on the page and the submit ad add button doesn't work.
If it is unticked, it means that they are mandatory but they disappear from the item_add page. weird.

Is theme or osclass 440 error?
 

Same problem on sigma theme?

Yes it is the same problem on sigma theme.
If are ticked on the new item_add are visible.
If it is unticked on the new item_add these two fields do not appear.
I have installed a new fresh 440 Osclass with a new data base and the theme is unchanged at all.

But if it is unticked, it means that they are mandatory but they disappear from the item_add page.
Something is wrong in osclass I think with these two options for users.

It simply means these fields will not be there. It has nothing to do with optional/required at all