python's webbrowser launches IE, instead of default browser, on Windows relative path

My main issue was a bad URL by attempting prepend file:// to a relative path. It can be fixed with this:

webbrowser.open('file://' + os.path.realpath(filename))

Using webbrowser.open will try multiple methods until one "succeeds", which is a loose definition.

The WindowsDefault class calls os.startfile() which fails and returns False. I can verify that by entering the URL in the windows run command and seeing an error message rather than a browser.

Both GenericBrowser and BackgroundBrowser will call subprocess.Popen() with an exe which will succeed, even with a bad URL, and return True. IE gives no indication of the issue, all other browsers have a nice messages saying they can't find the file.

1. GenericBrowser is set by the environment variable BROWSER and is first.
2. WindowsDefault is second.
3. BackgroundBrowser is last and includes the fall back IE if nothing else works.

Here is my original setup:

>>> import webbrowser
>>> webbrowser._tryorder
['windows-default',
 'C:\\Program Files\\Internet Explorer\\IEXPLORE.EXE']
>>> webbrowser._browsers.items()
[('windows-default', [<class 'webbrowser.WindowsDefault'>, None]),
 ('c:\\program files\\internet explorer\\iexplore.exe', [None, <webbrowser.BackgroundBrowser object at 0x00000000022E3898>])]
>>>

Here is my setup after modifiying the environment variables:

C:>path=C:\Program Files (x86)\Mozilla Firefox;%path%

C:>set BROWSER=C:\Users\Scott\AppData\Local\Google\Chrome\Application\chrome.exe

C:>python
Python 2.7.1 (r271:86832, Nov 27 2010, 17:19:03) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import webbrowser
>>> webbrowser._tryorder
['C:\\Users\\Scott\\AppData\\Local\\Google\\Chrome\\Application\\chrome.exe',
 'windows-default',
 'firefox',
 'C:\\Program Files\\Internet Explorer\\IEXPLORE.EXE']
>>> webbrowser._browsers.items()
[('windows-default', [<class 'webbrowser.WindowsDefault'>, None]),
 ('c:\\program files\\internet explorer\\iexplore.exe',[None, <webbrowser.BackgroundBrowser object at 0x000000000235E828>]),
 ('firefox', [None, <webbrowser.BackgroundBrowser object at 0x000000000235E780>]),
 ('c:\\users\\scott\\appdata\\local\\google\\chrome\\application\\chrome.exe', [None, <webbrowser.GenericBrowser object at 0x000000000235E8D0>])]
>>>

The webbrowser._tryorder gives the list of browsers tried. Registering chrome or adding a BROWSER env var or modifiying my path all would have gotten me the correct browser with a better error message.

Thanks for the help guys, I couldn't have solved this without your ideas.

You can use get(name) to use a specific browser.

You'll need to register the Chrome webbrowser, as it doesn't seem to be one of the predefined browser types, and then you should be able to do this:

webbrowser.get('chrome').open('http://www.google.com')

Update:

Actually, you might be able to just one of the following:

webbrowser.get('windows-default').open('http://www.google.com') webbrowser.get('macosx').open('http://www.google.com')

The docs show no predefined defaults for Linux.

This opened a new Chrome tab for me, and it's still OS-independent:

webbrowser.get().open('http://www.google.com')

What's odd is that without the get() call, it still uses IE. This looks like a bug with a simple workaround.

The webbrowser module is supposed to use the default browser, so this might be a bug. On the other hand, use this explanation from the docs to troubleshoot your problem:

If the environment variable BROWSER exists, it is interpreted to override the platform default list of browsers, as a os.pathsep-separated list of browsers to try in order. When the value of a list part contains the string %s, then it is interpreted as a literal browser command line to be used with the argument URL substituted for %s; if the part does not contain %s, it is simply interpreted as the name of the browser to launch.

Using Windows 10, in short, everything that does not include a full URL in the https://example.com format is opened in IE for me. For example, if I say

webbrowser.open("https://www.example.com")

it will open a new tab in Chrome, while

webbrowser.open("example.com")

will open IE. Any .get() will cause it to not open a browser at all.

Kind of weird behaviour, but I can see that this is a complex thing do implement and likely the OS is to blame for this behavior.