I have a DNN website version 5.6.1 that every once in a while would go off line and users would be directed to the install.aspx page. I had been told previously that this will happen if a website loses its connection to the database. It happened a number of times and I would contact the web host and they would tell me everything was fine. I would check my event viewer and never saw anything that would indicate what was causing the problem.
I found it odd/improbable that the website would lose its connection to the database because the files are stored on the same server as the database. It happened twice in the last week and I knew I had to find what was causing the issue. I had previously searched Google and the DNN forums for an answer. Out of desperation I put out a tweet to the DotNetNuke community and recieved a number of useful suggestions. Among them was this
useful link from Chris Paterra.
My Web.Config file was missing the InstallationDate key in the appSettings section.
"InstallationDate: This section is added during the initial installation of DotNetNuke. It will have a value that equals the date of that installation (1/2/2011 for example). When not present (and an install does exist) users could be redirected to the Install.aspx page."
I had moved the site a couple of times and somewhere along the way I must have removed the InstallationDate line from the web.config file thinking it wasn't necessary because that was the date I installed it on the old server and a new date would be generated for the new server. Bonehead!
I found the original install date in the CreatedDate field of the Version table and added the key back to the web.config.
<add key="InstallationDate" value="9/25/2009" />
I just wanted to post this so it would show up the the forum search and hopefully help somebody in the future. Since the problem was sporadic I won't actually know for sure until some time has passed and the site users haven't been directed to the install page but I feel pretty confident that was it.
Rich