Server Error in '/' Application. | asp.net c# [duplicate]

I am new to ASP.net C#. I have developed web application and it is running on my local machine without any issues. when I hosted the applicaiton on "somee.com", site is running and it is allowing me to login without any issues. when I click on on link from the navigation bar, it give me below error. "An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine."

<!-- Web.Config Configuration File -->
<configuration>
    <system.web>
        <customErrors mode="Off"/>
    </system.web>
</configuration>

Then i have placed the tag in web.config file and checked. it gives me another error

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
   SriluAutoInfo.Admin.Page_Load(Object sender, EventArgs e) +142
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +52
   System.Web.UI.Control.OnLoad(EventArgs e) +97
   System.Web.UI.Control.LoadRecursive() +61
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +693

appreciate your help on this case.

Note: Except one link all the other links are working fine.