recently working on workflow issues and try to find the way get all related message from different log.
below is the source I can get more information about the workflow :
- ULS log / C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\LOGS at the log look for the category of Workflow Infrastructure
- hidden workflow history lists
- SharePoint workflows, this list is located at http://yoursiteurl/Lists/Workflow History,
- For Nintex workflows, you can find it at http://yoursiteurl/Lists/NintexWorkflowHistory.
some useful article related with workflow: