The file format and extension of 'file.xlsx' don't match
Excel showed "The file format and extension of 'file.xlsx' don't match" because the filename and the bytes did not identify the same workbook format. FileFix can test whether damaged .xlsx package content remains and show you a free preview of limited watermarked pages of the recovered worksheets before you decide. A one-time $14 USD — and only if the repair works.
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Your files auto-delete — delete them sooner anytime
No person looks at your file as part of repair
We couldn't recover this one.
The file is too damaged to rebuild, so there is nothing to preview and no charge.
What stopped you continuing? One tap tells us why.
Try a deep repair
The repair engine can try a longer pass on the file you already uploaded.
Machine-only processing; no human views files; nothing is sent to an outside AI.
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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, OPUS, AIFF, XLSX, DOCX, PPTX, ODT, ZIP, RAR, PDF, AI, HEIC, and HEIF). We're adding support for more formats over time.
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Why this happens
This warning is an identity check. It appears when a file named .xlsx contains another format, or when damage to the ZIP package prevents Excel from recognizing the workbook structure the extension promises.
Renaming a file does not convert its contents. If the upload contains recoverable Excel package members, they can be placed into a fresh .xlsx; unrelated bytes cannot be turned into the expected workbook.
FileFix scans for workbook members, rebuilds recoverable worksheet and shared-string XML, and reports the watermarked worksheet pages from the output.
What we can and can't recover
We can usually fix
- Files that show "Excel found unreadable content"
- Files Excel calls an invalid format or extension
- Workbooks cut off mid-save or mid-transfer
- Files that show the right size but won't open
We can't fix
- Password-protected/encrypted workbooks
- Genuinely empty (0-byte) files
- Deleted or formatted files (that's data recovery, a different job)
- The old binary .xls format (this repair is for .xlsx)
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 watermarked pages of the recovered worksheets.
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Pay & download If the preview shows what you need, unlock the repaired Excel file for a one-time $14 USD.
You see watermarked pages from your rebuilt workbook before you decide anything — so you never guess.
See what's recoverable.
Free watermarked page preview · private & auto-deleted
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Questions
The filename says .xlsx, but Excel cannot recognize the expected workbook structure in the file. It may contain a different format, or damage to the .xlsx ZIP package may prevent recognition. The warning alone does not tell you which.
Renaming changes the filename, not the contents. If the file is a healthy .xls, CSV, or another spreadsheet format, open it in an app that supports that format and save or convert it to .xlsx. Renaming cannot restore missing workbook data.
Try downloading it again from the original source or ask the sender for a fresh copy. A failed download may save an incomplete file or an HTML error page under an .xlsx filename. Repair cannot recreate a spreadsheet that was never in the downloaded file.
If damaged .xlsx package content remains, FileFix can attempt to rebuild recoverable worksheets into a fresh .xlsx. It does not convert legacy .xls files or unrelated bytes into a workbook, and it cannot restore content missing from the upload.
If a workbook can be rebuilt, the free preview shows limited watermarked worksheet pages from that result. Check the visible content before checkout; a successful rebuild does not mean missing sheets or cells were recreated.