“Cannot open file as archive” — diagnosing a RAR that won't open at all
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The four usual suspects
1. It isn't actually a RAR. Files get renamed: a .zip or .7z with a .rar extension is the most common case. The real format is in the file's first bytes, not its name — Fileglass checks the signature and tells you what the file really is.
2. The download is incomplete or corrupted at the start. If the archive's header — its first few hundred bytes — is damaged, nothing can identify it. When the damage starts later, the intact part can still be read.
3. It's a very old RAR (1.x / 2.x, from the 1990s). Archives from old software or retro communities use header formats modern libraries dropped. Fileglass detects these and says so explicitly instead of a generic failure; extracting them needs vintage WinRAR on desktop.
4. It's a later volume of a multi-part set. Trying to
open archive.part2.rar or .r00 alone fails in
most tools. Open the first volume (.part1.rar or the plain
.rar) with all parts present.
Get the real diagnosis in seconds
Drop the stubborn file below. Fileglass reads its actual structure and tells you which of the four cases you're in — and if any files are readable, you'll get them. Everything runs locally in your browser.
More guides: CRC error · Unexpected end of archive · Cannot open as archive