I found a solution to this on Windows, and it turns out it also works on Ubuntu:
- Close Chrome
~/.config/google-chrome/Local State in a text editor.
- Search for
- To make Chrome ask you how to handle a specific protocol again, remove the line corresponding to that protocol in the list of excluded schemes.
- Save and exit.
protocol_handler has been moved to the file
Preferences in the subdirectory
Default. If you are using multiple profiles, the file is also located in the folders
Profile 3 etc.
protocol_handler no longer seems to exist, this is now handled directly within the Chrome settings, see https://support.google.com/chrome/forum/AAAAP1KN0B0_FSBtFo5g_8 . Currently it is found in Settings -> Privacy and Security -> Site settings -> Handlers