Today, while I was configuring a test farm for my client, I got stuck on a strange issue. Everything was configured by default. I had ran and installed the pre-requisite’s via the GUI, then installed the SharePoint features. Once this was complete, I ran the Config wizard which also completed successfully. Now when I am trying to browse to the Central Admin Site, It show the following error:

It is really strange for me as I never experience this issue before. I check the Central Admin’s web.config but no luck.

Root Cause:

Finally googling and digging into IIS, I found the root cause for this issue.

In the IIS > Management > Feature Delegation page, I found that Session State feature is marked as Read only. Which is causing the issue.

Resolution:

In order to fix the issue, please change the delegation to Read/Write.

•  Go to IIS Server

• Now Click on Feature Delegation
• Now on the Right Action Panel, Click on Read/Write.

• Now perform the IIS reset and test again.

Explanation about the Feature Delegation:

When you configure the delegation state of a feature from IIS Manager, you specify whether the feature’s related configuration section is locked or unlocked in the server-level configuration files (ApplicationHost.config and root Web.config) for IIS 8. When you lock a feature, configuration can only be read from and written to the server-level configuration file for that feature. However, you can unlock a feature when you want to read from or write to lower-level configuration files, such as a Web.config file in your site or application.

You can use Web.config files to read and save configuration settings for any or all features in your sites and applications. You can then easily copy configuration from one computer to another. For example, you might develop an application on a development or test computer and specify application features to write to Web.config. This lets you package all the application’s content easily, including its configuration file, and transfer it to another computer.

Feature Delegation pairs with the IIS Manager Users and IIS Manager Permissions features to enable non-administrative users to view and configure delegated features in their sites or applications by using IIS Manager. The delegation state of a feature determines whether users can configure the feature in their sites and applications. For example, if you want to let users configure data connection strings, select Connection Strings from the list on the Feature Delegation page, and then click Read/Write from the Actions pane or the right-click menu.

The Feature Delegation page affects all sites and applications on the Web server. The Feature Delegation settings that you configure at the server level are for all sites on the server; the settings that you configure at the site level are for all applications in that site. If you want to configure delegation states for features in a specific site or application, use the Custom Site Delegation and Custom Application Delegation pages.

Reference:   Feature Delegation