I'll log errors to the event log for just about any app that I write with something like the following:
EventLog eventLog = new EventLog();
eventLog.Source = "My App Name";
eventLog.WriteEntry(message, EventLogEntryType.Error);
This is no problem for a windows app, but for an asp.net app running under a restricted account, you'll likely get an error:
System.Security.SecurityException: Requested registry access is not allowed.
The issue described here recommends either adding the event source manually in the registry or creating an EventLogInstaller. Unless you're creating a commercial software package, you're probabaly going to go the registry route. The only issue here is that the article leaves a peice out. Adding only the key will allow your app to write to the event log but rather than your own neatly formatted error message you'll see:
The description for Event ID ( 0 ) in Source (<application name>) could not be found. It contains the following insertion string(s):
If you look at other keys you'll see they contain an "EventMessageFile" reg_expand_sz (expandable string value). Asp.net 2.0 or higher apps will have the value "c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\EventLogMessages.dll". If you want a quick fix, here's the reg file code (make sure you save as unicode):
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application\YourSourceNameHere]
"EventMessageFile"=hex(2):63,00,3a,00,5c,00,57,00,49,00,4e,00,44,00,4f,00,57,\
00,53,00,5c,00,4d,00,69,00,63,00,72,00,6f,00,73,00,6f,00,66,00,74,00,2e,00,\
4e,00,45,00,54,00,5c,00,46,00,72,00,61,00,6d,00,65,00,77,00,6f,00,72,00,6b,\
00,5c,00,76,00,32,00,2e,00,30,00,2e,00,35,00,30,00,37,00,32,00,37,00,5c,00,\
45,00,76,00,65,00,6e,00,74,00,4c,00,6f,00,67,00,4d,00,65,00,73,00,73,00,61,\
00,67,00,65,00,73,00,2e,00,64,00,6c,00,6c,00,00,00
Here's the .net 4.0 version....
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\Application\YourSourceNameHere]
"EventMessageFile"=hex(2):63,00,3a,00,5c,00,57,00,49,00,4e,00,44,00,4f,00,57,\
00,53,00,5c,00,4d,00,69,00,63,00,72,00,6f,00,73,00,6f,00,66,00,74,00,2e,00,\
4e,00,45,00,54,00,5c,00,46,00,72,00,61,00,6d,00,65,00,77,00,6f,00,72,00,6b,\
00,5c,00,76,00,34,00,2e,00,30,00,2e,00,33,00,30,00,33,00,31,00,39,00,5c,00,\
45,00,76,00,65,00,6e,00,74,00,4c,00,6f,00,67,00,4d,00,65,00,73,00,73,00,61,\
00,67,00,65,00,73,00,2e,00,64,00,6c,00,6c,00,00,00