The moment it fails
A backup or a project folder sent as one archive, and now the error says it is corrupted. One message stands between you and months of work, with no way to see what survived.
Why the archiver refuses it
ZIP lists its contents in a central directory at the very end, so an interrupted file loses its table of contents. Files compressed before the cut may be intact.
What happens to the file
Files inside are found by their own signatures, and a new valid archive is written with the intact ones. Each is then processed separately: a damaged video in a damaged ZIP can come back playable in a valid ZIP.
What you come away with
An archive that opens, and a report naming what was kept. Solid RAR and 7z archives compress many files as one stream, so damage affects what follows and fewer files remain. Encrypted content needs intact data and the password.
Common questions
Does it work with a multi-part archive?
Each file is read on its own, so one part gives only what it holds.
Is the folder structure kept?
Where names are intact, yes. The report flags files that lost theirs.
Sources
Documents consulted for this guide.