How do I set up my Response object to perform all of the necessary cleanup

This is my code, my application is in error inadvertently where the application will not load and throws an error. The only way to fix the issue is by recycling the app pool that the application runs under. But, I am wondering if my problem can be resolved by setting up this code correctly? For instance putting it in a using statement, which I am not certain how to do.

// Write PDF
Response.Clear();
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition", assessment);
Response.WriteFile(filepath3);
Response.End();

I don't know if this is related or not, but this is the Server error:

Server Error in '/Apps/LeadAssessmentApp' Application.
Creating an instance of the COM component with CLSID {080D0D78-F421-11D0-A36E-00C04FB950DC} from the IClassFactory failed due to the following error: 800401e4 Invalid syntax (Exception from HRESULT: 0x800401E4 (MK_E_SYNTAX)).
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.Runtime.InteropServices.COMException: Creating an instance of the COM component with CLSID {080D0D78-F421-11D0-A36E-00C04FB950DC} from the IClassFactory failed due to the following error: 800401e4 Invalid syntax (Exception from HRESULT: 0x800401E4 (MK_E_SYNTAX)).
    
Source Error:
    
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.