I cannot install Joomla (on Ubuntu 12.04, Apache, MySQL). All required prerequisites seem to be met, but after hitting the final install button, a popup appears (see attached image), but nothing happens. Also, a check on the server seems to indicate that no files or mysql activity takes place.
I retried with several different versions of Joomla, without success.
What can this be, or where can I look more closely what is supposed to happen at this very stuck moment?
The problem was simple (as always: at least in hindsight). A bad server configuration caused no errors or log entries server-side because the actual problem happened client-side: Following the suggestion made by Lodder, I checked the console output in Chrome and found complaints about Content-Security-Policy (which I had thought was still in Report-Only mode, but wasn't). In order for the installation to continue (and finish), the CSP policy needs to contain the (fairly insecure) setting script-src 'self' 'unsafe-inline' 'unsafe-eval'. Once I modified the CSP header accordingly, the installation went fine.
I wish that among the green check marks in the Pre-Installation Check table, there'd be one also checking this ...
busy == true. So at a guess, one of the Ajax calls has failed for some reason. Could you try running the installation again but with your browsers console open and report any errors if you see any – Lodder May 23 '16 at 11:22