In privacy and security settings I switched Opera to delete all cookies and wrote down few allowed sites, but despite that Opera deletes all cookies, also from sites I added to white-list. On Firefox such option works as intended, is there any way to do it on Opera too?

Wow, thanks, now I get how it works, I knew there must be some simple way to do it. Adding [*.] before URL.com does its job pretty well too. I should have paid more attention at the start.

Hey, if still someone's interested in this bug I know how to semi-fix it. You have to open Privacy and Security options and go to PDF documents pad. Here you have to turn on downloading .pdf files instead of autoopening them in Opera. Thanks to this action pdf doc embedded in the frame on the site gonna turn into URL and you will be able to save this page in .mhtml, just without pdf inside.

@leocg I did deeper testing and only some cookies remain, but still Chrome clears it all, while Opera leaves some cookies or "empty" containers like this one from https://naszamlawa.pl/
https://imgur.com/a/X23jHbA
in Chrome such thing like naszamlawa.pl in cookies data doesn't appear after closing browser. I use kinda the same settings on both Opera and Chrome.
Not that it's such a big problem, but I like to keep everything clean from trash. Would be cool if theres button to clear all cookies but leave ones I need. When I clean cookies by opera://settings/clearBrowserData then all cookies get deleted, also these from google and podatki.biz I set exception for.

@leocg Just tested on Chrome, there it works as intended, seems like only Opera has such problem.

I have an option to delete cookies activated when I close Opera, but it just doesn't work. Everytime I close it everything stays. I use just 2 exceptions. In Firefox similar option works perfectly fine, what's wrong with Opera on this one? I don't want to manually delete cookies after every session and I want cookies for google and one more site to stay to keep me logged in.
https://imgur.com/a/fHlHFjX

I have a problem with Opera launcher or assistant poping up annoying adware-like window in bottom right corner on my second pc with Windows 7, where I have Opera installed but use it much less than on my main pc where I open it everyday (I guess problem would be the same on W10 if I don't open it regulary). This is how this window looks like https://imgur.com/a/dNTt7MF I always tick this box not to show up again, but it doest every few days/weeks. I have opera launcher turned off at start so I guess it opens up only after update that is checked everyday in task manager. Is there any way to get rid of this pup? Can i just delete assistant folder in Opera appdata or it may mess up autoupdate feature? I'm not really interested in all these new stuff, Opera is perfect as it is, I just hate pups like that, I stopped using whole Magix software because of such thing...

Hey, if still someone's interested in this bug I know how to semi-fix it. You have to open Privacy and Security options and go to PDF documents pad. Here you have to turn on downloading .pdf files instead of autoopening them in Opera. Thanks to this action pdf doc embedded in the frame on the site gonna turn into URL and you will be able to save this page in .mhtml, just without pdf inside.

Wow, thanks, now I get how it works, I knew there must be some simple way to do it. Adding [*.] before URL.com does its job pretty well too. I should have paid more attention at the start.

In privacy and security settings I switched Opera to delete all cookies and wrote down few allowed sites, but despite that Opera deletes all cookies, also from sites I added to white-list. On Firefox such option works as intended, is there any way to do it on Opera too?

Thanks for the answers, yep, for sure something is wrong with current engie as in older versions I can save this page properly. Hope it gonna be fixed sooner or later but it's not a big deal since I can use older version for this specific site.

@burnout426 Interesting it's default option now. Year ago I made thread about mhtml flag being completly removed and someone advised me to force mhtml saveing by changing target. After one of the updates I noticed that mhtml files get saved as html, however I checked shortcut on my desktop and noticed that this specific line got removed from it. I added "--save-page-as-mhtml=1" back to the target and bug with wrong file extension disappeared, it saves mhtml with correct name now.

Hello, I have problem with new Opera builds, I force them to save pages as mhtml by adding "--save-page-as-mhtml=1" to launcher.exe, it still works which is cool, however one blog has notes that can't be saves this way. Saving gets interrupted and file is not created, relaunching download creates broken file. For example I can't save this one:
https://kodluch.wordpress.com/2020/05/26/26-05-2020-syria-1697-dzien-sprzatania-swiata/

I could understand it as mhtml is not fully supported anymore but... I still have opera 12.15 as secondary option for mht and this old one still saves these notes without any problem. Files created this way can be easily opened with newest Opera and are working fine. Any idea what blocks newest builds from saving such page properly while old one does it without any problem?

Site still doesn't work on Opera. I checked on another pc, here it also doesn't work. First laptop has Windows 10 installed, second Windows 7. Both systems fully updated, Opera is also the newest version. No problems on any other browser.