I’ve been in the situation a few times with ASP.Net applications where someone says to you ‘I got this error on screen when I did x, I don’t know what it said but i couldn’t work.’

Odds are you have got an unhanded exception in your web application, but how are you meant to debug it when the error has long gone? Elmah (error logging and error handling modules for asp.net) may well be your saviour. Download it out now from http://code.google.com/p/elmah/

So, what does it do?

Well, once you have it configured on your application or server, every time something causes an unhanded exception it will log it into a database, send you an email alert and fix the code for you (last part was a joke!). So, now when the user tells you they have had an problem you can look in the system and see exactly what happened.

The application is open source, and is based on the article at http://msdn.microsoft.com/en-us/library/aa479332.aspx, check that article out if you want to know more about how it was written

Installing it

You can run it in two ways, on a particular web application or at the server level. As I was a bit confused at first as to how to set it up, here is a quick guide to installing it for an individual application and log the errors onto a SQL 2000 server.

1. Download the zip file from the website, if you are using dotnet 2.0 you will need the latest beta version.
2. Extract the files, in the src/Elmah/ folder find the Database.sql script. This is the script that will build the tables it needs. Create a new database and run this script on the database
3. Next, go into the bin/net-2.0/Release/ folder, and copy the Elmah.dll and Elmah.xml files into you applications /bin folder
4. Once you have the assembly, you need to configure your application to use it. You do this by adding some sections into your applications web.config file. In the /samples folder there is an example web.config file you can get all the information out of to put in your file. For the most part it is easy to follow, but I had a couple of problems.
5. The first one was the database connection, make sure you add a new connection to your <connectionStrings> section that points at the database you have created.
6. You then need to point to this connection in the connectionStringName section of the elmah errorLog.
7. Once you have added the other sections into your config file you should just be able to browse to your site /elmah.axd to see your errors

You can also configure options such as getting it to send an email when an exception occurs, subscribe to the log as an rss feed etc.

So now you should have a handy reference point for all your exemptions. You can tell the user you are looking into there problem before they even report it to you!

I’ve been doing a bit of tweaking on a SQL Reporting Services install this week, trying to get it to run a bit better, get better logs out of it and generally try and improve its performance. So, what did I do?

Reports Timing out – This is a pain. I have a couple of reports that people run huge queries for, and sometimes the reports can time out while running. This was a fairly easy fix, just locate your rsreportserver.config file (mine was in (Program Files\Microsoft SQL Server\MSSQL.2\Reporting Services\ReportServer). Open it up and alter the key:

DatabaseQueryTimeout- This is the amount of time the reports server will wait until it thinks the query to the server has timed out. You can set it to 0 (zero) for no timeout, but this is probably not a good idea. There is another key in there I thought might also help called SQLCommandTimeoutSeconds but according to the MS docs this is not used (so why the hell is it in there?)

Better Client Side Errors – Fault finding errors in the report viewer can be a bit painful, but you can enable remote errors to help you out a bit.
There  is a table in the reports server database called ConfigurationInfo. In here there is a EnableRemoteErrors property. If you set this to true and restart the reporting service clients will get better errors, helping you try and work out what is actually happening.

My next step with errors is to try and handle them properly in the reports. There is a ReportError event witch I think will do the trick. When I have worked out the best way to use it i will post about it here

Logs – As well as writing to the application event log, reporting services also write more detailed information into its own log files. These (along with crash dump files) can be found in C:\Program Files\Microsoft SQL Server\MSSQL.2\Reporting Services\LogFiles.

Using all this info I now find it easier to troubleshoot and tweek my environment. If anyone else has any handy hints let me know and ill add them to this post!