I have faced this issue on a fresh install, version 2017.2. Uninstalling everything and installing fresh did not help at all.
Logs here %localappdata%\Unity\Editor\ shows something like below
Error loading file:///C%3A%2FUsers%2FYOURUSERNAME%2FAppData%2FRoaming%2FUnity%2FPackages%2Fnode_modules%2Funity-editor-home%2Fdist/index.html#/login
To fix
go to C:\Program Files\Unity\Editor\Data\Resources\Packages
You can see 4 tgz files
1. unity-editor-home.0.8.30.tgz
2. unityeditor-cloud-hub-0.0.15.tgz
3. unityeditor-collab-history.0.6.14.tgz
4. unityeditor-collab-toolbar.0.7.15.tgz
Use an unarchive program (I used 7-zip file manager) to open each one of these and extract contents (dist folder and package.json file) to your Roaming folder
C:\Users\YOURUSERNAME\AppData\Roaming\Unity\Packages\node_modules
After extract, the folder looks like this..
..\AppData\Roaming\Unity\Packages\node_modules\unity-editor-home
..\AppData\Roaming\Unity\Packages\node_modules\unityeditor-cloud-hub
..\AppData\Roaming\Unity\Packages\node_modules\unityeditor-collab-history
..\AppData\Roaming\Unity\Packages\node_modules\unityeditor-collab-toolbar
and as an example, unity-editor-home like below (one level subfolders shown)
..\AppData\Roaming\Unity\Packages\node_modules\unity-editor-home\dist
..\AppData\Roaming\Unity\Packages\node_modules\unity-editor-home\package.json
..\AppData\Roaming\Unity\Packages\node_modules\unity-editor-home\README.md
