7-Zip returns the following exit codes:
| Code | Meaning |
|---|---|
| 0 | No error |
| 1 | Warning (Non fatal error(s)). For example, one or more files were locked by some other application, so they were not compressed. |
| 2 | Fatal error |
| 7 | Command line error |
| 8 | Not enough memory for operation |
| 255 | User stopped the process |