Weird consequences of full transaction logs

Let say that you have an ASP.Net 2.0 web application running on top of MSSQL Server 2005. Guess what happen if you database transaction log get full? Well, you will get a large amount of weird side effects, most of them seeming totally unrelated to the saturation of the transaction log.

Among the problems that I have encountered

• The web services of your website start to send totally misleading error messages like authentication failed.

• You can not login through web form into your ASP.Net application any more. You will not get any error message, but the login control just tells you that your password is wrong.

• You look at your error logs (like ELMAH), but nothing gets recorded.

• You decide to go through the “recover password” (because you’re still no suspecting the transaction logs), but actually it fails and no email is sent.

For the note, the following SQL question clears your transaction logs
DUMP TRANSACTION mydatabase WITH NO_LOG