Error Handler “PageHandlerFactory-Integrated” has a bad module “ManagedPipelineHandler” in its module list

How to get rid of this error Handler “PageHandlerFactory-Integrated” has a bad module “ManagedPipelineHandler” in its module list 

The problem is that which version of .Net you are using has not been registered with IIS correctly. Perform the following actions. 

Navigate to  Start -> All Program -> Accessories  right click on Command Prompt and then Run as administrator

If you are using .Net version 4 on a 64-bit 2008 server use these two commands to fix it.

%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -i 

It will start Installing ASP.NET (v4.0.30319)

 I hope it will resolve your problem.

After this when I tried to run my application on IIS then I got the following database login error.

Cannot open database "Database name" requested by the login. The login failed. Login failed for user 'IIS APPPool\ASP.NET v4.0'.

Change the identity of used Application Pools.

Select the Advanced Setting of your used Application Pools. Change the Identity from ApplicationPoolIdentity to LocalSystem. 

Now run your application and I hope it will resolve your database login error also.