Application Log Warning for Event 1309

Log Name:      Application
Source:        ASP.NET 4.0.30319.0
Date:          12/11/2011 9:35:30 PM
Event ID:      1309
Task Category: Web Event
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      SecureAuth01.TheEntDomain.local
Description:
Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 12/11/2011 9:35:30 PM 
Event time (UTC): 12/12/2011 5:35:30 AM 
Event ID: be9517ae3d884bfc84804dd9823052bc 
Event sequence: 23 
Event occurrence: 1 
Event detail code: 0 
 
Application information: 
    Application domain: /LM/W3SVC/1/ROOT/SecureAuth45-6-129681416581752281 
    Trust level: Full 
    Application Virtual Path: /SecureAuth45 
    Application Path: D:\SecureAuth\SecureAuth45\ 
    Machine name: SECUREAUTH01 
 
Process information: 
    Process ID: 1696 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\NETWORK SERVICE 
 
Exception information: 
    Exception type: FormatException 
    Exception message: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or a non-white space character among the padding characters. 
   at System.Convert.FromBase64String(String s)
   at MFC.WebApp.SecureAuth.createpfx.Page_Load(Object sender, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
 
 
Request information: 
    Request URL: https://secureauthdemo.gosecureauth.com:443/secureauth45/Authorized/createpfx.aspx 
    Request path: /secureauth45/Authorized/createpfx.aspx 
    User host address: 70.181.120.133 
    User: .ASPXFORMSAUTH 
    Is authenticated: True 
    Authentication Type: Forms 
    Thread account name: NT AUTHORITY\NETWORK SERVICE 
 
Thread information: 
    Thread ID: 6 
    Thread account name: NT AUTHORITY\NETWORK SERVICE 
    Is impersonating: False 
    Stack trace:    at System.Convert.FromBase64String(String s)
   at MFC.WebApp.SecureAuth.createpfx.Page_Load(Object sender, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
 
 
Custom event details: 

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="ASP.NET 4.0.30319.0" />
    <EventID Qualifiers="32768">1309</EventID>
    <Level>3</Level>
    <Task>3</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2011-12-12T05:35:30.000000000Z" />
    <EventRecordID>4781</EventRecordID>
    <Channel>Application</Channel>
    <Computer>SecureAuth01.TheEntDomain.local</Computer>
    <Security />
  </System>
  <EventData>
    <Data>3005</Data>
    <Data>An unhandled exception has occurred.</Data>
    <Data>12/11/2011 9:35:30 PM</Data>
    <Data>12/12/2011 5:35:30 AM</Data>
    <Data>be9517ae3d884bfc84804dd9823052bc</Data>
    <Data>23</Data>
    <Data>1</Data>
    <Data>0</Data>
    <Data>/LM/W3SVC/1/ROOT/SecureAuth45-6-129681416581752281</Data>
    <Data>Full</Data>
    <Data>/SecureAuth45</Data>
    <Data>D:\SecureAuth\SecureAuth45\</Data>
    <Data>SECUREAUTH01</Data>
    <Data>
    </Data>
    <Data>1696</Data>
    <Data>w3wp.exe</Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>FormatException</Data>
    <Data>The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or a non-white space character among the padding characters. 
   at System.Convert.FromBase64String(String s)
   at MFC.WebApp.SecureAuth.createpfx.Page_Load(Object sender, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
</Data>
    <Data>https://secureauthdemo.gosecureauth.com:443/secureauth45/Authorized/createpfx.aspx</Data>
    <Data>/secureauth45/Authorized/createpfx.aspx</Data>
    <Data>70.181.120.133</Data>
    <Data>.ASPXFORMSAUTH</Data>
    <Data>True</Data>
    <Data>Forms</Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>6</Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>False</Data>
    <Data>   at System.Convert.FromBase64String(String s)
   at MFC.WebApp.SecureAuth.createpfx.Page_Load(Object sender, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
</Data>
  </EventData>
</Event>