How to make a portable version of Opera the default browser?

The following method worked for me to set OperaPortable as default browser to open external http and https links.

I checked it using Windows 7 x64 Pro SP1 and latest official OperaPortable version 58.0.3135.47 downloaded from Opera.com.

1) Create text file and paste text:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\OperaHTML]
@="Opera HTML"

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\OperaHTML\DefaultIcon]
@="C:\\port\\OperaPortable\\launcher.exe,0"

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\OperaHTML\shell]

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\OperaHTML\shell\open]

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\OperaHTML\shell\open\command]
@="\"C:\\port\\OperaPortable\\launcher.exe\" -- \"%1\""


[HKEY_CURRENT_USER\Software\Classes\https\DefaultIcon]
@="C:\\port\\OperaPortable\\launcher.exe,0"

[HKEY_CURRENT_USER\Software\Classes\http\DefaultIcon]
@="C:\\port\\OperaPortable\\launcher.exe,0"

[HKEY_CURRENT_USER\Software\Classes\https\shell\open\command]
@="\"C:\\port\\OperaPortable\\launcher.exe\" -- \"%1\""


[HKEY_CURRENT_USER\Software\Classes\http\shell\open\command]
@="\"C:\\port\\OperaPortable\\launcher.exe\" -- \"%1\""

[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\https\UserChoice]
"Progid"="OperaHTML"

[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice]
"Progid"="OperaHTML"

2) Change the path to launcher.exe (in my example it's C:\port\OperaPortable\launcher.exe) Don't delete double slashes.

3) save file with .reg extension, run and confirm it. Association should work after that (no need reboot).

If you need ftp-links also - add at the end of reg file at step 2.

[HKEY_CURRENT_USER\Software\Classes\ftp\DefaultIcon]
@="C:\\port\\OperaPortable\\launcher.exe,0"

[HKEY_CURRENT_USER\Software\Classes\ftp\shell\open\command]
@="\"C:\\port\\OperaPortable\\launcher.exe\" -- \"%1\""

For html-files association just use as usual Shift + mouse Right click > Open with > and find your PortableBrowser in explorer.