Refreshing or Cleaning Your Profile

Ayespy

Reinstalling Vivaldi to fix a problem is almost never necessary, and almost never helpful. It may happen, however, that some of your user files get into conflict with each other or the program, or become corrupt. You can "reset" Vivaldi to "factory condition" in such a case. We call this a refresh or a cleaning of your profile.

Occasionally a moderator or a user may recommend that you "refresh" or "clean" your profile to see if it will fix a problem. One way to do this without losing all of your user data, is as follows:
0. Make sure your system is set to display Hidden files.

Open Vivaldi and access the Main Menu (the "V" button at the top left or the horizontal menu at top if you have elected to show the menu that way), going to Help > About (or by typing vivaldi://about into the address bar).
In the resulting window, you will see an item labeled Profile Path. This tells you where your Default folder is. Default is the folder we will be working with. Note where it is.
Close Vivaldi and go to the folder on your hard drive that contains your Default folder. Rename the Default folder. You may name it anything you like, even Bernice.
Re-open Vivaldi, and test whether the problem is fixed. You will notice that all of your settings and data have disappeared. Have no fear.
If the problem is fixed, close Vivaldi again and go back to the folder that contains your old, renamed profile, plus your shiny brand new Default folder that Vivaldi made when you restarted it. Move critical data such as Bookmarks, Favicons, Login Data, history, cookies, etc. from Bernice to Default (check the "Back up some Vivaldi information" section in this article). You may even move the Top Sites file over, if you aren't keen to re-fetch all of your Speed Dial Thumbnails, etc., but old, over-sized Top Sites files have sometimes been implicated in slow running and high resource usage. DO NOT restore your Extensions files and folders. They are frequently the cause of the original problem you had.
Open Vivaldi and pick the settings and appearance you like. Re-install your extensions, one at a time, testing after each to ensure that a given extension doesn't break Vivaldi again. If it does, uninstall it and don't use it again.

And there you are! A fresh, clean copy of Vivaldi, good as new, and working correctly. Now you can save Bernice for a while to make sure she's not holding some forgotten data you needed, or you can delete her. She's fulfilled her purpose. Enjoy your new browsing experience!

Isildur

As it isn't obvious:
For for copying search engines over from the old profile, copy the directory mpognobbkildjkofajifpdfhcoklimli

e.g.
OS X: /Users/[user]/Library/Application Support/Vivaldi/Default-old/Local App Settings/mpognobbkildjkofajifpdfhcoklimli
or
Windows: c:\users[username]\AppData\Local\Vivaldi\User Data\Default\Local App Settings\mpognobbkildjkofajifpdfhcoklimli\

(as noted in this old thread)

Ayespy

I'm locking this topic so that it's a pure resource. If a user has info they feel should be added to it, please message me and we'll put it up together. Thanks for understanding.

ayespy

Gwen-Dragon

Resetting a profile is describe in Vivaldi Help (F1) page.