Fix: can not delete install subfolder after upgrading phpBB on IIS
To upgrade a phpBB forum, one usually downloads an automatic upgrade package to the latest version, selecting on the website which version they currently have. The current version number at a phpBB installation is shown at the Admin Control Panel (there’s a link to it at the bottom of the main page of a phpBB forum usually) and there admins also see a warning if they have older version and links/info on how to upgrade.
After the correct automatic upgrade package is download, the install subfolder it contains has to be unpacked into the forum folder on the webserver. From that point on the forum is taken offline and users can’t log-in or see discussions anymore till the install subfolder is deleted.
The installation process is quite smooth, you just point the browser to the install subfolder (say http://localhost/myforum/install) and then it will show a step-by-step wizard, where it first updates the database to the latest version and then shows option to update the PHP files and other file resources at the forum either via FTP automatically or by creating an archive on the fly that you can download and unpack into the forum’s folder on the webserver, replacing any previous files with the same path/filename as the ones in the archive, without closing the upgrade wizard webpage. Then you tell the wizard to check again if files are now updated and you’re done.
However, there’s one last and very important step to bring the forum online again and let users log-in again to it and/or see discussions. You have to remove the install subfolder you had placed at the forum folder on the webserver.
If you use IIS (note that you can easily install WordPress and PHP on IIS using Microsoft Web Platform Installer), you may find that you can’t delete some subfolders nested a bit deeper under the install subfolder, like db and en.
I just had this issue while upgrading phpBB on http://robotics.mech.upatras.gr/forum and had tried various ways to delete the install folder, like the handy Take Ownership command on the Windows Explorer folder context menu, to no avail – that is till I realized it was IIS that was blocking deletion of those subfolders. So I opened up IIS Manager, did a Stop action on the webserver (it might have also worked if I had just stopped the respective website) and then I could delete the install folder from Windows Explorer. Started IIS again and all was up and running nicely.