I had exactly the same problem after updating Tor Browser. I found a file at
~ is an abbreviation for
~/.local/ folder is a hidden folder. To toggle show/hide hidden files and folders press the keyboard combination Ctrl+H or click the three horizontal lines icon ≡ in the upper right corner of Files application and put a checkmark next to the Show Hidden Files option. When I right-clicked this file and selected Open, Tor Browser opened successfully.
Then I used the information in Properties -> Basic tab -> Command: of the start-tor-browser.desktop file to update my Tor Browser launcher so that I could open Tor Browser as usual by clicking on its icon in the Dash.
If this happens again I'm going to check the start-tor-browser.desktop file again to see if it works, because apparently Tor Browser updates only the start-tor-browser.desktop file, but it does not update the Tor Browser icon that you can find in the Dash. This Tor Browser launcher must be updated manually.
The desktop launcher for Tor Browser is located at
/usr/share/applications/torbrowser.desktop. To change the properties of the Tor Browser desktop launcher requires sudo. Open the terminal and type:
sudo nano '/usr/share/applications/torbrowser.desktop'
If your Ubuntu username is
user change the line in torbrowser.desktop that starts with
Exec=sh -c '"/home/user/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/Browser/start-tor-browser" --detach || ([ ! -x "/home/user/.local/share/torbrowser/tbb/x86_64/tor-browser_en-US/Browser/start-tor-browser" ] && "$(dirname "$*")"/Browser/start-tor-browser --detach)' dummy %k
Because nano text editor does not support line wrapping you will need to use the arrow keys to move the mouse cursor to the end of the line to make sure that you copied the entire line correctly before you save the changes that you made to torbrowser.desktop.
The instructions for using nano editor are always found at the bottom of every page. The only two nano keyboard shortcuts that you need to know are for WriteOut and Exit. Press the keyboard combination Ctrl+O and after that press Enter to save the file being edited. Press the keyboard combination Ctrl+X to exit nano.