"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.
Free preview — pay only if you download ($5)
Your files auto-delete within 48 hours
No person looks at your file as part of repair
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Recovering what we can.
Analyzing your file...
Here's what we recovered.
Review the watermarked preview before checkout. Previews are capped at 90 seconds.
Repair your file
Choose a supported file to see what can be repaired before checkout.
Simulated checkout — no payment is processed.
Optional — we'll email your private download link.
Download repaired fileYou preview before you pay. If the download is materially worse than the preview you approved, we'll refund you.
Good news — your file isn't damaged. No charge.
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.
We couldn't recover this one.
The file is too damaged to rebuild, so there is nothing to preview and no charge. You can try another file.
Have another clip from the same device?
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.
FileFix can't fix that kind of file yet.
Right now we repair video, audio, and document files (MP4, MOV, M4V, MKV, AVI, TS, MTS, M2TS, MPG, MPEG, VOB, 3GP, WebM, M4A, WAV, MP3, AAC, FLAC, OGG, AIFF, XLSX, DOCX, ZIP, and PDF). We're adding support for more formats over time.
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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.
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 · files auto-delete within 48 hours
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Questions
The engine scans the archive bytes for each surviving local file header, decompresses the readable entry data, and writes those entries into a new ZIP with a fresh index.
It shows how many entries are in the rebuilt archive, how many can be read, and a file list with names and sizes. Long lists may be shortened in the on-page summary.
It preserves bytes emitted from a damaged compressed stream when possible, but a truncated member may be incomplete. Missing bytes cannot be reconstructed. The recovered-file list and readability count describe the rebuilt archive, not the completeness of every file's contents.
No. The archive carries entry names and paths in its local records. FileFix works from the ZIP file you upload.
No. The engine does not decrypt archive entries or bypass passwords.
No. A split archive depends on all of its numbered parts. FileFix cannot manufacture a missing part or fetch it from the source.
A one-time $5 — and only if the repair works. The recovered-file summary is free, and checkout is unavailable if the engine cannot produce a rebuilt archive with recovered members.
No person does. The engine automatically decompresses entries to rebuild and verify the archive. Files auto-delete within 48 hours.
The current scan handles stored entries and standard DEFLATE entries. An entry using a different compression method may not be included in the rebuilt archive.
No. FileFix repairs an archive file you still have. Recovering a deleted file from a drive or memory card is a separate data-recovery task.
A CRC mismatch means the decompressed bytes do not match the checksum stored in the damaged entry record. The scanner can preserve bytes it emitted, but that mismatch is evidence the member may be incomplete or altered.
ZIP readability checks whether an entry can be read from the new container. They do not validate the internal rules of every file format inside it. A recovered document or image can still contain its own damage.
The scanner enforces entry-count, decompressed-size, and compression-ratio limits. Archives that exceed those safety bounds are rejected rather than expanded without a limit.