If you turn off the friendly errors in the K2 web.config file you get Cast from type 'DBNull' to type 'String' is not valid.

This can occur because of the following.

 K2LogArchive database is incorrect.

In this instance the K2 Log Archive database was copied by the DBA's and then the new copy was renamed this is not the proper procedure for this.

Here is the procedure:

Keep in mind that if you run into the same problem that I did you will need to put in the same name that they already changed it to so it will recognize the existing data.

Logged in as an account that has admin rights to k2 and dbo rights to the K2 Server. 

Click on StartàControl PanelàAdd or Remove Programs

Click on Change  for K2.net 2003 Archiving Components (3.6262.1.0)

Click Next

Click Modify then click Next

Click Next

Click Next

Click Next

In the Database: field put in the name of the new database that you are going to be using and click Next.

Finish out with any defaults and you will be good to go.