Yesterday everything worked fine but when i tried to open my DNN Page i got a "500 Internal Server Error.

Here is the Error Log:

2018-12-14 09:15:16,516 [Test][Thread:52][ERROR] DotNetNuke.Services.Exceptions.Exceptions - DotNetNuke.Services.Exceptions.PageLoadException: The given key was not present in the dictionary. ---> System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.

at System.ThrowHelper.ThrowKeyNotFoundException()

at System.Collections.Generic.Dictionary`2.get_Item(TKey key)

at DotNetNuke.Entities.Tabs.TabInfo.CheckIfDoctypeConfigExists()

at DotNetNuke.Entities.Tabs.TabInfo.get_SkinDoctype()

at DotNetNuke.Framework.DefaultPage.SetSkinDoctype()

at DotNetNuke.Framework.DefaultPage.OnInit(EventArgs e)

at System.Web.UI.Control.InitRecursive(Control namingContainer)

at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)