On Windows, the profile path is probably:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\

So the folder to examine is:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions\

In there, you'll probably find two "Session_" files, and two "Tabs_" files. The sizes of the files are hints as to which ones have all your open windows/tabs (big files contain lots of tabs/windows).

You'll probably find that the newest ones are small, and the oldest ones are larger; if that is the case, then deleting the new/small ones may enable Opera to recover your tabs/windows.

Chrome works the same way, but I've found that to get Chrome to prompt me with an offer to recover the closed tabs/windows, it needs to have been aborted, rather than closed gracefully, the last time it closed -- and killing it from Task Manager does NOT work to cause an abort! I have to kill it from Process Explorer, instead! I don't know whether the same thing is true with Opera, but I assume that it probably is.

So, if Opera loses your open tabs & windows, my recommendation is that you do the following:

First, save a copy of the contents of this folder (probably four files), to a temporary location somewhere:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions\

Second , abort Opera using Process Explorer.

Third, delete the new/small Tabs_* and perhaps Session_* files, leaving the older/larger versions, in the "C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions" folder.

Fourth, restart Opera, and allow it to restore your closed tabs/windows.

If that doesn't recover them, you can go back to the Second step above (abort Opera), then restore your saved Tabs_* and/or Session_* files into the "C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions" folder, and try deleting different one(s) (e.g., perhaps just the latest Tabs_* file).

(Note: I cobbled together a .bat script which runs whenever Windows restarts, to save the contents of the last few versions of Chrome's Sessions folder, to further reduce the risk of losing them. I haven't bothered to do the same thing with Opera, yet, but I probably will, because I'm starting to use Opera more and more.)

I started out just looking for a "safe mode" command-line switch, like all the other browsers have; e.g.:

C:\Program Files (x86)\Opera>launcher --disable-extensions

I couldn't find it.

So, my question is, where can I find documentation for Opera's command-line parameters?

I'm using Opera for Windows, version 63.0.3368.53 (about to restart to update to 63.0.3368.71).

The list of command-line switches / options / parameters for Opera used to be here:
https://www.opera.com/docs/switches/

It's gone, now. This seems to be the final version:
https://web.archive.org/web/20180412125335/https://www.opera.com/docs/switches/

It seems to have little resemblance to version 63 reality.

There's also a big list of Chromium command-line parameters here:
https://peter.sh/experiments/chromium-command-line-switches/

I've only tried a few of them with Opera, and I didn't find any that work.

A few command-line parameters seem to be recognized, even though they don't work right:

--version or -version or /version doesn't display the version number unless you redirect the output into a file, but it does prevent Opera from opening a new window

--help or -help or /help is similar. It doesn't seem to work at all if you run it via launcher.exe, but if you run the desired version of opera.exe directly, and redirect output into a file, like this:

"C:\Program Files (x86)\63.0.3368.71\opera" --help >tmp.txt

Then the resulting tmp.txt file contains:

Opera 63.0.3368.71 Stable
Features available through command-line switches:
	--with-feature:better-address-bar [Enabled by default: true]
	--with-feature:captive-portal-interstitial [Enabled by default: true]
	--with-feature:chrome-extensions-one-click-install-policy [Enabled by default: true]
	--with-feature:chromium-ua-compatibility [Enabled by default: false]
	--with-feature:crypto-wallet [Enabled by default: true]
	--with-feature:crypto-wallet-ios-instructions [Enabled by default: true]
	--with-feature:crypto-wallet-new-server [Enabled by default: true]
	--with-feature:lookalike-url-navigation-suggestions [Enabled by default: true]
	--with-feature:notification-overlay-on-taskbar [Enabled by default: false]
	--with-feature:partner-bookmarks-opt-out [Enabled by default: true]
	--with-feature:reborn-3-dropdown [Enabled by default: false]
	--with-feature:reborn-communicator-show-permissions [Enabled by default: true]
	--with-feature:search-results-extensions-block-v2 [Enabled by default: true]
	--with-feature:sd-flicker-buster [Enabled by default: false]
	--with-feature:toolkit-bookmarks [Enabled by default: false]
	--with-feature:update-recovery-page [Enabled by default: true]
	--with-feature:wallpapers-api [Enabled by default: true]
	--with-feature:warn-on-closing-multiple-tabs [Enabled by default: true]
	--with-feature:yandex-zen-news [Enabled by default: false]
	--with-feature:zoom-indicator [Enabled by default: true]
	--with-feature:personal-news-notifications [Enabled by default: true]
Press any key to continue . . .

Well, it's not specific to Opera. I download the web page and stripped out all the javascript, and then it happened in every web browser. So it's an archive dot org quirk, not an Opera quirk:

https://sealevel.info/Archive_dot_org_quirk_avascript-disabled2.html

Sorry for the false alarm!

I did some more checks, and discovered that it happens only when javascript is disabled. (I have the "Enable Javascript" extension installed in Opera.) Here are four screenshots.

First, here's a screenshot showing the quirk:
https://sealevel.info/Opera_Archive_dot_org_quirk_demo1_javascript-disabled.png

When javascript is enabled, the quirk does not happen:
https://sealevel.info/Opera_Archive_dot_org_quirk_demo2_javascript-enabled.png

Archive.is does not exhibit the quirk:
https://sealevel.info/Opera_Archive_dot_org_quirk_demo4_archive_dot_is.png

Viewing the original text file in Opera (not the copy from archive.org) also shows no quirk:
https://sealevel.info/Opera_Archive_dot_org_quirk_demo3_no_Archive_dot_org.png

I encountered a strange problem today.

Here's a plain text file:

https://sealevel.info/BEST_vs_UAH_2020-06-14h_digitization_notes.txt

Here's the WayBack Machine's copy:

http://web.archive.org/web/20200616135432/https://sealevel.info/BEST_vs_UAH_2020-06-14h_digitization_notes.txt

When I view that archived copy in Chrome, Firefox, Edge, Brave, PaleMoon or Vivaldi, it looks fine. But in Opera (Version:78.0.4093.231 or 79.0.4143.22 stable 64-bit on Windows 10) it only shows about ten lines of the file, in a little borderless window. Scrolling is possible with arrow keys, and there's a scrollbar near the right-edge of the window (which I didn't notice at first).

I don't know whether this is a bug, or merely a six-legged feechur, but I don't like it.

@fcarruth, it definitely happens in Chrome, sometimes.

I've posted a detailed comment about what to do, here:
https://forums.opera.com/topic/47146/recovering-lost-tabs-after-restart?_=1613315508111

On Windows, the profile path is probably:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\

So the folder to examine is:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions\

In there, you'll probably find two "Session_" files, and two "Tabs_" files. The sizes of the files are hints as to which ones have all your open windows/tabs (big files contain lots of tabs/windows).

You'll probably find that the newest ones are small, and the oldest ones are larger; if that is the case, then deleting the new/small ones may enable Opera to recover your tabs/windows.

Chrome works the same way, but I've found that to get Chrome to prompt me with an offer to recover the closed tabs/windows, it needs to have been aborted, rather than closed gracefully, the last time it closed -- and killing it from Task Manager does NOT work to cause an abort! I have to kill it from Process Explorer, instead! I don't know whether the same thing is true with Opera, but I assume that it probably is.

So, if Opera loses your open tabs & windows, my recommendation is that you do the following:

First, save a copy of the contents of this folder (probably four files), to a temporary location somewhere:

C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions\

Second , abort Opera using Process Explorer.

Third, delete the new/small Tabs_* and perhaps Session_* files, leaving the older/larger versions, in the "C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions" folder.

Fourth, restart Opera, and allow it to restore your closed tabs/windows.

If that doesn't recover them, you can go back to the Second step above (abort Opera), then restore your saved Tabs_* and/or Session_* files into the "C:\Users\yournamehere\AppData\Roaming\Opera Software\Opera Stable\Sessions" folder, and try deleting different one(s) (e.g., perhaps just the latest Tabs_* file).

(Note: I cobbled together a .bat script which runs whenever Windows restarts, to save the contents of the last few versions of Chrome's Sessions folder, to further reduce the risk of losing them. I haven't bothered to do the same thing with Opera, yet, but I probably will, because I'm starting to use Opera more and more.)

Re: Spam advertisement/extension?

I just had a spam advertisement pop-up in Opera Version:73.0.3856.344 (Update stream: Stable, System: Windows 10 64-bit (WoW64)). It is extremely obnoxious, covering up a 352x292 pixel block in every tab. Here's a screenshot:

https://sealevel.info/ad_inserted_into_Opera_draw_a_heart_with_Snapshot_on_Valentines_Day_screenshot01.png

I have few extensions in Opera, but just yesterday I'd installed the Redirect Bypasser v.2.1.3 extension by Moises Lima, so I initially suspected it as the culprit. But I disabled it, and the pop-up spam ad is still there, even in a new tab. So I don't think it is to blame.

Here's a screenshot showing the spam advertisement covering part of the "Extensions" page:

https://sealevel.info/ad_inserted_into_Opera_draw_a_heart_with_Snapshot_on_Valentines_Day_screenshot02.png

Today is Valentine's day, 2021. It apparently happened to some people last year on Valentine's Day, too. There's a discussion here:

https://forums.opera.com/topic/38350/spam-advertisement-extension?_=1613307548847

That discussion includes a screenshot of the same ad, but in Norwegian, rather than English:

https://i.imgur.com/TCUkV7Z.png

It was never resolved in that discussion who/what is to blame, but the majority opinion was that it's the Opera developers, themselves, who created this spam ad, to advertise Opera's snapshot feature.

Say it ain't so, Opera! Surely the browser with the built-in ad blocker would not insert a spam ad on top of every web page!?!??

I started out just looking for a "safe mode" command-line switch, like all the other browsers have; e.g.:

C:\Program Files (x86)\Opera>launcher --disable-extensions

I couldn't find it.

So, my question is, where can I find documentation for Opera's command-line parameters?

I'm using Opera for Windows, version 63.0.3368.53 (about to restart to update to 63.0.3368.71).

The list of command-line switches / options / parameters for Opera used to be here:
https://www.opera.com/docs/switches/

It's gone, now. This seems to be the final version:
https://web.archive.org/web/20180412125335/https://www.opera.com/docs/switches/

It seems to have little resemblance to version 63 reality.

There's also a big list of Chromium command-line parameters here:
https://peter.sh/experiments/chromium-command-line-switches/

I've only tried a few of them with Opera, and I didn't find any that work.

A few command-line parameters seem to be recognized, even though they don't work right:

--version or -version or /version doesn't display the version number unless you redirect the output into a file, but it does prevent Opera from opening a new window

--help or -help or /help is similar. It doesn't seem to work at all if you run it via launcher.exe, but if you run the desired version of opera.exe directly, and redirect output into a file, like this:

"C:\Program Files (x86)\63.0.3368.71\opera" --help >tmp.txt

Then the resulting tmp.txt file contains:

Opera 63.0.3368.71 Stable
Features available through command-line switches:
	--with-feature:better-address-bar [Enabled by default: true]
	--with-feature:captive-portal-interstitial [Enabled by default: true]
	--with-feature:chrome-extensions-one-click-install-policy [Enabled by default: true]
	--with-feature:chromium-ua-compatibility [Enabled by default: false]
	--with-feature:crypto-wallet [Enabled by default: true]
	--with-feature:crypto-wallet-ios-instructions [Enabled by default: true]
	--with-feature:crypto-wallet-new-server [Enabled by default: true]
	--with-feature:lookalike-url-navigation-suggestions [Enabled by default: true]
	--with-feature:notification-overlay-on-taskbar [Enabled by default: false]
	--with-feature:partner-bookmarks-opt-out [Enabled by default: true]
	--with-feature:reborn-3-dropdown [Enabled by default: false]
	--with-feature:reborn-communicator-show-permissions [Enabled by default: true]
	--with-feature:search-results-extensions-block-v2 [Enabled by default: true]
	--with-feature:sd-flicker-buster [Enabled by default: false]
	--with-feature:toolkit-bookmarks [Enabled by default: false]
	--with-feature:update-recovery-page [Enabled by default: true]
	--with-feature:wallpapers-api [Enabled by default: true]
	--with-feature:warn-on-closing-multiple-tabs [Enabled by default: true]
	--with-feature:yandex-zen-news [Enabled by default: false]
	--with-feature:zoom-indicator [Enabled by default: true]
	--with-feature:personal-news-notifications [Enabled by default: true]
Press any key to continue . . .

It works for me, too, just like in CeeDee's screenshot... when the Opera icon is there. But every so often (maybe once a month?), Opera gets unpinned from my taskbar.

I wondered whether it could be happening when Opera updates itself, but I don't think that's it. Opera just updated itself from version 56.0.3051.116 to version 57.0.3098.76 without unpinning itself. So it doesn't happen with every update, anyhow.

It's not a big problem. I just go to the start menu, find it, and re-pin it to the taskbar.

But my other browsers don't do that. I have seven browsers pinned to my taskbar, and the only one that keeps going away is Opera.

(This is Windows 10 Home, 64-bit.)

The [VPN] indicator in the address bar in an InPrivate window is very misleading. It does not mean that VPN is enabled. It is actually a "button" which you can use to enable or disable VPN, and its color changes depending on whether VPN is enabled or disabled.

That might be why you think VPN isn't working -- because it's actually not enabled.

Here's a screenshot with VPN disabled:
http://geeksalive.com/opera_inprivate_with_vpn_disabled_screenshot.png

Here's a screenshot with VPN enabled:
http://geeksalive.com/opera_inprivate_with_vpn_enabled_screenshot.png

SUGGESTION: Hey, Opera developers, if you see this: please change the "no VPN" indicator to have a slash through it or similar, so that users don't think they have VPN enabled when they don't!