Attention, Google Chrome users.
In a recent update in Chrome canary and dev channels, Google Chrome can't install userscripts from sources outside the Google Play Store. If you try to click on "Install" on a userscript.org page, you'll get the warning "Extensions, apps and user scripts cannot be installed from this web site", and nothing happens.
According to this post in a Chromium issue discussione:
"This change was made to protect users. Off-store extensions have become a popular attack vector for compromising users of larger sites (e.g. Facebook). Since the trend is only getting worse, we're putting the power back in the user's hands by allowing them to control where extensions are installed from. By default, the Chrome Webstore is the only source, but users and administrators will be able to add other safe sources as they see fit."
This is some odd decision that tries to secure the noob but actually annoys the experienced. There *is* a workaround, though:
1. download the userscript you want to install;
2. open the url chrome://chrome/extensions/ ;
3. drag the userscript .user.js file and drop it to the page above.
At the present time, there's no way to revert to the old behaviour, not a flag in the chrome://flags page, not even a command line option. I hope this won't land on the stable channel before some changes, like a flag "Enable installing extensions, apps and user scripts from unknown sources" (Android style) or even better a management of a secure web site list in the settings page.
hopefully this helps some people out