When starting Vivaldi browser on your device, you might be getting a following error message shown:
Your profile could not be opened correctly Some features may be unavailable. Please check that the profile exists and you have permission to read and write its contents.
In addition to that, you might be missing website icons on your bookmarks, or some other issues.
This error can be caused by missing files or wrong permissions on your profile folders, and seems to be happening mostly on Linux machines, but can show on Windows devices also.
If you have not made any changes to your system, it could be caused by hung or frozen Vivaldi processes preventing the access to all the necessary data.
Check for multiple Vivaldi processes
Before making any changes to your profile files and folders, check for a possible stale processes using Task Manager.
Right click on your taskbar, and open Task Manager from the menu.
Go to Processes tab, and check if you have multiple Vivaldi processes shown there.
Right click on those processes, and click on End task, to kill the process.
After you have killed all the processes, try to reopen browser again, to check if you will still have any errors on application startup.
Helpful links:
https://vivaldi.net/en-US/forum/vivaldi-browser-for-linux/10903-profile-can-t-be-opened-correctly