Launch debugging any existing Debug Log file
In the Logs folder in your project, you have the files that were downloaded from Salesforce by you (you can do this in such a way: the
Main Menu ⇒ View ⇒ Pads ⇒ Logs ⇒ Download Logs). Just open the necessary log file in the Debug view in the IDE and look through all the important information. To do this, go to the Main Menu:
Run ⇒ Debug from a log file.
In addition, you can start the debugging process directly from your Salesforce log file: just open a downloaded log with the configured debug levels which are required for the debug and select the Start Debugging option from the context menu.
This option gives you almost unlimited possibilities: you are able to run the Debugger even if you have a Production org, having only the logs and the current version of the code.
NB: The log file should have the minimal required log level. If the log level of your log file is insufficient, you will see the error message.
In this section:
This also may be useful: