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HomeHomeUsing DNN Platf...Using DNN Platf...Administration ...Administration ...404 Error for all pages except home page404 Error for all pages except home page
New Post
1/6/2016 4:36 AM


My DNN 7.4.1 site has been running fine for several weeks. Suddenly, all pages except home page started giving 404 error message. I restarted application by recycling the application pool and that brought my site back. Just wondering what caused the issue in the first place. There is nothing unusual in DNN Logs or Event Viewer on the server. DNN Log is filled with 404 error entries for last 12 hours.

Please advise how can I prevent this from re-occurring. From my investigation so far, it could be possibly related to URL Routing but web.config already contains this:

"UrlRoutingModule-4.0" />
  "UrlRoutingModule-4.0" type="System.Web.Routing.UrlRoutingModule" preCondition="" />


I am using IIS 7.5 with ASP.NET 4.5 on a Windows 2008 Server R2 64bit machine. 

Many thanks
Arif Shah

New Post
1/7/2016 10:28 AM
Since a app pool recycle fixed your issue... I suspect you have an server specific issue going on. Something probably overloaded your app pool.

Two links that may help...
New Post
1/10/2016 3:10 PM

I have the same errors see post:

In my case the most time these errors occur after there is a app pool restart. The standard IIS recycle or sometimes after installing a module that also restarts the app pool.

I don’t think I has anything to do with an overloaded your app pool.

On one instance I don’t let IIS recycle the app pool. On that instance I don’t see the 404 error’s any more.


Met vriendelijke groet, Han Peper
New Post
1/10/2016 8:41 PM
I don't have access to either box. Hard for me to say. If you have problems when you do an app pool restart and this thread's user fixes his issues with an app pool restart then my gut tells me you are dealing with different issues. I'm wrong frequently however.

Have you both reviewed your HTTPERR directory. It is possible something may be logged there that might be helpful. If you have access to your box directly then it would be worth looking.

It may be in a different location for your box...

New Post
3/22/2018 12:40 AM

I believe that this is due to the code that fetches the tab dictionary not being thread safe. When multiple requests are made to a site it's possible that an empty tab dictionary becomes cached and therefore all requests return a 404 response until the application pool is recycled.

Further details and a code fix can be found at:

Hope this helps others.
HomeHomeUsing DNN Platf...Using DNN Platf...Administration ...Administration ...404 Error for all pages except home page404 Error for all pages except home page

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