Obfuscator version 3.1 added a StackTrace unobfuscator allowing you to receive a StackTrace matching you original source code.
The first step you have to do is to enable the saving of the obfuscator renaming mapping.
To do this, go to Unity->Window->Obfuscator Settings->Advanced, scroll to the bottom and activate the save of the mapping.
Next step is to set a file path for the saved mapping. For example C:\Users\Me\Documents\ObfuscatorMapping.txt.
Now build you game with active obfuscator.
When you receive now a error copy the stack trace and go to Unity->Window->Obfuscator StackStrace,
enter in the top textarea your stack trace and press the ‘Try to unobfuscate’ button.
Internally, the obfuscator loads your Mapping, you stored at the first step, and tries to unobfuscate the stack trace and shows it in the bottom textarea.