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The file cannot be read or is refused

What to do when a file is refused on upload or the page says This file could not be processed: every message, its cause and the fix, for spreadsheets, CSV files and ZIPs.

  • 6 min read
  • Updated October 13, 2026
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A file can be turned away in two places, and the message tells you which.

  • When you drop it: the message appears in red under the drop area, and no upload is started. Nothing was stored.
  • While it is read: the upload's page shows This file could not be processed with the reason, Retry, Edit configuration and a drop area, Or upload a corrected file.
The red message under a configuration's drop area after a file of the wrong type was chosen
A file of the wrong type is turned away when you choose it: the message (1) appears under the drop area and nothing is uploaded.
The page of a file that could not be processed, with the reason, Retry, and the drop area for a corrected file
A file that could not be processed: the reason, Retry, and the drop area for a corrected file.

Neither costs anything: no record write is used, and nothing reaches your site.

Symptoms#

  • Red text under the drop area when you choose a file, and no new upload appears.
  • This file could not be processed, with a sentence under it.
  • A message beginning This workbook…, This file…, The ZIP…, Cells must… or Use at most….

Likely causes#

Confirmed (each reproduced in our tests, or read from the program's own checks):

  1. The file is not a spreadsheet type at all (a PDF, a Word document, an image).
  2. The workbook is protected with a password, or it is saved as .xlsb or by Apple Numbers.
  3. A web page or XML file was saved with a spreadsheet name (some systems "export to Excel" like this).
  4. A CSV is not UTF-8 (saved as ANSI or Windows-1252) and holds an accent or symbol.
  5. The header row is empty, has a repeated name or a name longer than 200 bytes, or the file has a header and nothing else. (An empty cell in it is fine: that column is named by its position.) Often the file has no header row at all, and its first item is being read as the column names: the message then adds Row 1 looks like data, not column names.
  6. The file is over a limit: rows, columns, cell size, row size or total text.
  7. A ZIP has no spreadsheet, two spreadsheets, a password, or paths that leave the archive.

Possible (depends on the file; try the steps below if none of the above fits):

  • A workbook that was damaged when it was copied, emailed or synchronised.
  • An old .xls workbook that is very large or full of objects.

Step-by-step solution#

  1. Read the message on the page. It names the problem. The table below says what to do for each.
  2. Open the file yourself in Excel, LibreOffice or Google Sheets. If it does not open there, it is damaged: go back to the original or an earlier copy.
  3. Save a clean copy: File → Save As → Excel Workbook (.xlsx) or CSV UTF-8. A fresh copy removes passwords, macros, odd structures and old formats.
  4. Upload the copy by dropping it on the configuration's card, or on the drop area of the failed file's page.
Message What to do
The file field must have one of the following extensions: csv, tsv, txt, xlsx, xlsm, xls, ods, zip. Save the data as .xlsx or CSV. A PDF or Word table must be copied into a spreadsheet first.
This workbook is password-protected… / This spreadsheet is password-protected… Remove the password (Excel: File → Info → Protect Workbook → Encrypt with Password, clear it) and save.
This .xls workbook cannot be read… / …took too long to read… / …damaged or too large to read… Open it in Excel and save as .xlsx.
Excel binary workbooks (.xlsb) are not supported… Save as .xlsx, .ods or CSV.
Apple Numbers files are not supported… In Numbers: File → Export To → Excel or CSV.
This file is a web page or XML document, not a spreadsheet… Open it in Excel, then Save As .xlsx or CSV.
This file is damaged or not a spreadsheet… / This file is not a readable ODS spreadsheet… / This workbook is unsupported… Open the file, and if it opens, save it again under a new name as .xlsx. If it will not open, use an earlier copy.
Cells must contain valid UTF-8 text of at most 32 KB. Almost always the encoding: save as CSV UTF-8 (character encoding). Otherwise a cell is longer than 32 KB (large files).
The first row must contain unique column names of at most 200 bytes. Fix the header row: no two columns with the same name (column headers).
Row 1 is empty: delete the empty rows above the column names, or, if the file has none, read it without a header row. Delete the blank rows above the column names. If the file has no column names at all, read it without a header row (files without a header row).
Add a header row and at least one non-empty data row. Add the data under the header.
Either of the two, followed by Row 1 looks like data, not column names: if the file has no header row, read it again as a file without one. If the file has no header row, select Read it without a header row and map its columns, Column A, Column B and so on (files without a header row). Otherwise fix the header row as above.
Add at least one row with values. The file, read without a header row, is empty: upload the right file.
Use at most 10,000 data rows and 100 columns. Split the file or remove unused columns (large files).
Use at most 128 KB of text per row and 25 MB of text per import. Shorten the longest rows; split the file.
Spreadsheets must be at most 10 MB. / This file is larger than 40 MB. / ZIP files must be at most 25 MB. Slim the file down or split it (large files).
The ZIP contains no spreadsheet… Add the spreadsheet to the ZIP, or drop the spreadsheet next to the ZIP (ZIPs).
Choose a spreadsheet and one ZIP of images, or a single ZIP that contains both. You dropped two spreadsheets, or two ZIPs. Drop one of each.
The ZIP could not be read… / The ZIP is damaged… / The ZIP is password-protected… / The ZIP contains files that point outside it… Make the ZIP again from a folder, without a password.
The ZIP contains more than 2,000 files… / The ZIP expands to more than 200 MB… Split the images over several uploads; images already sent are remembered (reusing images).

How to verify#

  • The new upload's page shows Reading your file, then What will change, with the number of rows you expect (the header does not count; without a header row, every row does).
  • Open one new item in the review and compare its title and body with your spreadsheet: accents and symbols should look right.

If it persists#

  • Retry is only for a problem that was temporary; it reads the same file again, so it cannot fix a bad file.
  • Try the same data as CSV UTF-8 instead of a workbook, or as a workbook instead of a CSV: if one works, the other file had the problem.
  • Check that the file opens from where you upload it: a file that is still being synchronised from a cloud folder can be incomplete.
  • If a file that opens fine everywhere is still refused, contact support with the exact message and the file (without secrets).

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