When an obfuscated program throws an exception, the resulting stack trace typically isn't very informative. Class names and method names have been replaced by short meaningless strings. Source file names and line numbers are missing altogether. While this may be intentional, it can also be inconvenient when debugging problems.
| Original code | - ProGuard → | Obfuscated code |
| ↓ | ↓ | |
| Mapping file | ↓ | |
| ↓ | ↓ | |
| Readable stack trace | ← ReTrace - | Obfuscated stack trace |
ReTrace can read an obfuscated stack trace and restore it to what it would look like without obfuscation. The restoration is based on the mapping file that ProGuard can write out during obfuscation. The mapping file links the original class names and class member names to their obfuscated names.