Extension Doesn´t install and now?

The most common reason for an Ulauncher Extension crash when install, is a missing Python dependency.
If you see an error like this, it´s mostly the cause.

        Message: 'com.github.brpaz.ulauncher-docsearch'
        Error Name: UnhandledError
        Type: KeyError

        Traceback (most recent call last):
        File "/usr/lib/python3/dist-packages/ulauncher/ui/windows/PreferencesUlauncherDialog.py", line 198, in
        on_scheme_callback
        resp = rt.dispatch(self, scheme_request.get_uri())
        File "/usr/lib/python3/dist-packages/ulauncher/utils/Router.py", line 49, in dispatch
        return callback(context, url_params)
        File "/usr/lib/python3/dist-packages/ulauncher/ui/windows/PreferencesUlauncherDialog.py", line 433, in
        prefs_extension_update_prefs
        controller = ExtensionServer.get_instance().get_controller(ext_id)
        File "/usr/lib/python3/dist-packages/ulauncher/api/server/ExtensionServer.py", line 76, in get_controller
        return self.controllers[extension_id]
        KeyError: 'com.github.brpaz.ulauncher-docsearch'
      

The solution

Search in the project README for the list of required dependencies and install them as specified.

In most cases, this can be done with Python Pip.

For example, the docsearch extension, requires the alogliasearch package to work.

It can be installed like:

  pip3 install algoliasearch '>2.0,<3.0'

After that, restart Ulauncher and the extension should work.

If you have the version 5.7.5 or greater of Ulauncher, it will display a warning message when installing the extension:

  ulauncher -v --dev |& grep "extension-name"