Orchard newbie here. I was playing around with installing and previewing themes from the galley when I suddenly started getting an error message when installing themes:
Package installation failed: There was an error installing the requested package. This can happen if the server does not have write access to the '~/Modules' or '~/Themes' folder of the web site. If the site is running in shared hosted environement,
adding write access to these folders sometimes needs to be done manually through the Hoster control panel. Once Themes and Modules have been installed, it is recommended to remove write access to these folders.
I also get an error installing modules. I set my Modules and Themes folders to full permission for all users but I still get the error. I googled and saw that many people had this issue and fixed it by changing the galley URL, but mine is already correct.