@leocg I left the option to encrypt all data checked, and yes I changed my password recently, so is this long sync password actually the old opera password? if that's the case it doesn't make sense, there should be a description that indicates this in the browser itself,
How are we users going to know this? I'm going to try to use other passwords that I've already made, if it works I'll give you an answer.

That's it for now, thanks!

I had to format my computer, and when I installed the opera browser again I tried to synchronize my bookmarks, however it asked for a long synchronization password which I had never seen before, which is preventing my synchronization.
Searching about I saw that several users have the same problem and we couldn't find a way to manage it, there is nowhere in the opera settings an option to create this long password, how can I synchronize my data if I never want to I created this password,
and the browser itself had never required this password to sync my data, before I had already done this process without needing a master password, why did this appear out of nowhere? and where can I create or recover this password so I don't have this problem again,
the help that opera provides is to clean all my synced data which causes them to be lost.
This situation is quite complicated for me, because I want access to my bookmarks and I have no way to access them,
if i do as suggested and reset all my data what guarantee do i have that this will not happen again? there is not even an option to create this long password, how will I be safe in saving new bookmarks?
If anyone can help me I'd be grateful!