Hi, we've got a dnn site which is running for about 2 years now, it's got several subportals, and we're running in 4.4.0.
Everything was working ok, untill some days ago.

When I try to add a page, and click submit, I get directed to the home page.
I can't see the newly created page in the menu right away, but when I look in the database, I can see it is there.
When I go to admin > pages, sometimes, I see the page, and sometimes I don't.
When it is there, and I click on the edit button, I get this error in the eventlog:

InnerException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

And:

Message: DotNetNuke.Services.Exceptions.ModuleLoadException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index ---> System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index at System.Collections.ArrayList.get_Item(Int32 index) at DotNetNuke.Modules.Admin.Tabs.Tabs.EditTab() at DotNetNuke.Modules.Admin.Tabs.Tabs.EditBtn_Click(Object sender, ImageClickEventArgs e) --- End of inner exception stack trace ---

In other words, It cant find the page, although I know it is in the database.

Does anybody know what this could be?

I was running 4.8.4 and had the same issue but just on one site.

I changed the app pool setting and all seems well now.

This is kind of weird? Does changing the app pool settings on one pool change it for all?

I looked after I made the change at my other app pools and they all had 1 for max. But I was not sure if they already had 1 or if they all changed when I changed this one site. If not, then what would have made this one site default to 2?