Reply to your public ticket #2666 error installing on offline site [Event Gallery Extended]
I installed Event Gallery Extended on a new site that was offline (global configuration/site offline yes)
After install, I received error messages, i.a., the com_eventgallery was not installed. I could not open the Eventgallery component, system said that com_eventgallery was not existing.
I deinstalled all and reinstalled, same messages.
I than put the site online (global configuration/site offline no) and could than access event gallery.
Once I could access the access the event gallery component on the online site, I than put the site (which is to be the production site) back offline and could access the event gallery component normally.