PowUpload can write occured exceptions logs to Event Viewer. To turn on this feature set in Web.Config file logExceptions parameter to "true" and make steps below:
By default, the user token of the ASP.NET worker process is ASPNET
(or NetworkService for applications that run on Internet Information
Services [IIS] 6.0). The problem that account does not have the correct user rights to create an event source.
RESOLUTION
Create an event source under the Application event log in Registry Editor. To do this, follow these steps:
1. Click Start, and then click Run.
2. In the Open text box, type regedit.
3. Locate the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application
4. Right-click the Application subkey, point to New, and then click Key.
5. Type PowUpload for the key name.
6. Right-click the PowUpload key, point to New, and then click String Value
7. Type EventMessageFile for the value name.
8. Right-click the EventMessageFile value, and then click Modify
9. Type C:\Windows\Microsoft.NET\Framework\v1.1.4322\EventLogMessages.dll for the value data.
Replace [C:\Windows] with your Windows system folder and [v1.1.4322] with your current .NET Framework version.
10. Close Registry Editor.