The password manager deleted all my passwords and it no longer wants to keep any of them. It no longer offers me to save them even though the function is activated. I can't even manually add a password.
Does anyone know what I can do?

@sgunhouse Yes, I too thought that Opera couldn't open the password store. But I don't know where this database is stored. On an old version of Opera, I had this problem and solved it by deleting the file in which the passwords were stored. But today it's much less simple.
I tried to completely destroy the "263" folder. A new folder was recreated when Opera opened and the password manager started working again. But a new problem arose: I could no longer change the browser language which remained stuck in English.

@myswtest Thank you for your answer.
I tested Opera with Flatpack but it was impossible to change the default language of the web browser. In addition, Opera no longer displayed X and Netflix videos. However, the configuration was correct. I installed Opera from a .deb file and the problem was the same.
Only with Snap can I have both Netflix and put the browser in French. But it only works for the time between two updates.

As for the desktop shortcut solution, as far as I know it is no longer possible to create shortcuts to an application on the Ubuntu desktop.

@myswtest This is the normal method. Unfortunately it does not work correctly. If you completely reinstalled Ubuntu and put Opera back on your PC, you would see that you would no longer have access to Netflix, because the permission to play protected content would not be enabled. The problem, is that if you went to the settings and activated this function, it would not be taken into account and the Netflix videos would still not be playable. The same goes for the browser's default language. You can change the settings as you like, English will always remain the default language.

@tobiasitalo Agora é o arquivo opera_opera.desktop que deve ser modificado para que a mudança de idioma tenha efeito. Mas, infelizmente, isso só durará até a próxima atualização. Depois disso, ele voltará para o inglês e você terá que modificar o arquivo opera_opera.desktop novamente.

And bam! New Opera update, and English becomes the default browser language AGAIN. I think this is because the Opera control panel on Linux does not work: The browser does not take into account the parameters you enter. Today, if you are installing Opera for the first time on Ubuntu,
you will no longer be able to watch Netflix. And it's irremediable because the browser takes no account of the settings you select.

So my request will probably remain unanswered but I'll ask it anyway: Does anyone know of another way to access Opera's configuration?

@myswtest Thank you for your answer.
I tested Opera with Flatpack but it was impossible to change the default language of the web browser. In addition, Opera no longer displayed X and Netflix videos. However, the configuration was correct. I installed Opera from a .deb file and the problem was the same.
Only with Snap can I have both Netflix and put the browser in French. But it only works for the time between two updates.

As for the desktop shortcut solution, as far as I know it is no longer possible to create shortcuts to an application on the Ubuntu desktop.

Opera's default language systematically reverts to English each time the web browser is updated. To successfully change the default language I must modify the opera_opera.desktop file located in «var/lib/snapd/desktop/applications» and replace «Exec=(...) snap/bin/opera %U» by «Exec=(. ..) snap/bin/opera --lang=fr %U»
However, the modification is canceled with each update.

Does anyone know of a way to keep the default language setting?

I managed to fix the problem by completely destroying the "263" folder in order to force Opera to recreate a new one. Of course before, I had made a copy of the original file. From this copy, I selected the “Extensions” and “Extensions Scripts” folders as well as the “Bookmarks” and “Preferences” files then I copied and pasted them into the new folder.

As for the language problem. I found in the "263" folder, a file called opera_opera.desktop. I made the changes recommended for the Opera.desktop file on this one.
I lost my passwords, my addresses as well as my favorite search engines, but I was able to solve the problem. I could have avoided destroying everything if I had known where the passwords were stored so that I only destroy this single data file.
But it works again; That is what matters.

@sgunhouse Yes, I too thought that Opera couldn't open the password store. But I don't know where this database is stored. On an old version of Opera, I had this problem and solved it by deleting the file in which the passwords were stored. But today it's much less simple.
I tried to completely destroy the "263" folder. A new folder was recreated when Opera opened and the password manager started working again. But a new problem arose: I could no longer change the browser language which remained stuck in English.

The password manager deleted all my passwords and it no longer wants to keep any of them. It no longer offers me to save them even though the function is activated. I can't even manually add a password.
Does anyone know what I can do?