"CRC failed" / "Data error" — what it means for a ZIP.
"CRC failed" or "Data error" means an extracted member does not match the checksum stored in the ZIP archive. Upload the archive for a repair attempt and see a free list of the members FileFix can place into a rebuilt ZIP before you decide.
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There's nothing to repair. If it still looks broken, the issue may be the player, codec, or viewer on your device rather than the file itself.
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A healthy video recorded on the same device — ideally the same settings — gives the repair engine a template to rebuild from. It can unlock repairs that fail on their own.
Unrepaired files are kept encrypted for up to 30 days, then deleted.
FileFix can't fix that kind of file yet.
Right now we repair video, audio, document, and image files (MP4, MOV, M4V, MKV, AVI, TS, MTS, M2TS, MPG, MPEG, VOB, 3GP, WebM, FLV, M4A, WAV, MP3, AAC, FLAC, OGG, AIFF, XLSX, DOCX, PPTX, ODT, ZIP, PDF, AI, HEIC, and HEIF). We're adding support for more formats over time.
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FileFix can often repair this kind of damage if the file is recoverable.
Why this happens
Each ZIP member stores a CRC checksum calculated from its original uncompressed bytes. An archive tool reports "CRC failed" or "Data error" when decompression produces different bytes, which indicates that the member data, its compressed stream, or the stored checksum was altered or cut off.
This is member-level damage rather than only a missing central directory. Other entries can remain intact, and a damaged DEFLATE stream may emit some bytes before it fails, but the checksum mismatch is evidence that the affected recovered member may be incomplete or changed.
There are checks you can run before deciding anything. Extract the other files first — most tools will continue past the failed member, and 7-Zip's "keep broken files" extraction option even preserves the damaged member's partial output. If the archive is still downloadable from its source, a fresh download is worth one attempt, since damage introduced in transit is a common cause of this error.
When the damaged member is the one you actually need, a rebuild cannot recreate the missing bytes — nothing can — but it can preserve everything that still reads cleanly and carry over what the damaged stream emitted before failing. The free file list shows the rebuilt archive's contents up front, so you can see whether the entry you care about made it before any question of paying.
FileFix scans local records, decompresses readable stored and DEFLATE data under safety limits, and writes recovered members into a new ZIP with a fresh directory. The free summary lists what the rebuilt archive contains; it does not certify the internal completeness of a member whose bytes were damaged.
What we can and can't recover
We can usually fix
- Archives that show "unexpected end of archive"
- Archives cut off during a download or copy
- ZIP files with a damaged central directory
- Archives that show the right size but won't open
We can't fix
- Encrypted archives
- Multi-part or split archives missing their other parts
- Genuinely empty (0-byte) files
- Files on physically damaged drives (that's hardware data recovery)
How it works
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Upload Drop the file in. It uploads over an encrypted connection. The repair runs automatically — no person looks at your file.
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Free Watermarked Preview You see exactly what we recovered — the list of files recovered from the archive.
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Pay & Download If the summary shows what you need, unlock the repaired ZIP archive for a one-time $5.
You see a recovery summary built from your actual file before you decide anything — so you never guess.
See what's recoverable.
Free recovery summary · private & auto-deleted
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Questions
Every member of a ZIP stores a checksum of its original bytes. When extraction produces bytes whose checksum doesn't match, the tool reports CRC failed — the recovered data disagrees with what the archive says it should be. It is a per-file failure, not a verdict on the whole archive.
No. The checksum failure belongs to a specific member. Other entries frequently extract and verify normally, which you can confirm by extracting them individually or by reading the free rebuilt-archive file list.
Sometimes, partially. Extractors can keep the bytes a damaged stream produced before failing — that is what 7-Zip's keep-broken-files option does — and the rebuild preserves the same partial output as a member of the fresh archive. Whether that partial content is usable depends on the file format inside.
The archive's bytes changed between creation and extraction: an interrupted or altered transfer, a bad sector on the drive or memory card, or an upload that was cut off. The checksum is doing its job — flagging that what arrived is not byte-for-byte what was packed.
No. FileFix can place readable recovered members into a new ZIP and list them in the free summary, but it cannot certify missing or altered bytes inside a damaged member.
A one-time $5 — and only if the repair works. Seeing what was recovered is free, and checkout is only offered when the engine produces a validated repaired file.