qax-os/excelize · error

ErrWorkbookFileFormat

ErrWorkbookFileFormat

Error message

unsupported workbook file format

What it means

ErrWorkbookFileFormat indicates that an encrypted workbook's EncryptedPackage stream is malformed — specifically shorter than packageOffset bytes — so the library cannot parse the package. decryptPackage and openReaderAt return it when the encrypted file structure does not meet the minimum size requirements.

Source

Thrown at errors.go:206

	ErrUnprotectWorkbook = errors.New("workbook has set no protect")
	// ErrUnprotectWorkbookPassword defined the error message on remove workbook
	// protection with password verification failed.
	ErrUnprotectWorkbookPassword = errors.New("workbook protect password not match")
	// ErrUnsupportedEncryptMechanism defined the error message on unsupported
	// encryption mechanism.
	ErrUnsupportedEncryptMechanism = errors.New("unsupported encryption mechanism")
	// ErrUnsupportedHashAlgorithm defined the error message on unsupported
	// hash algorithm.
	ErrUnsupportedHashAlgorithm = errors.New("unsupported hash algorithm")
	// ErrUnsupportedNumberFormat defined the error message on unsupported
	// number format expression.
	ErrUnsupportedNumberFormat = errors.New("unsupported number format token")
	// ErrUnsupportedPivotTableShowValuesAsType defined the error message on
	// receiving the unsupported pivot table "show values as" type.
	ErrUnsupportedPivotTableShowValuesAsType = errors.New("unsupported pivot table show values as type")
	// ErrWorkbookFileFormat defined the error message on receive an
	// unsupported workbook file format.
	ErrWorkbookFileFormat = errors.New("unsupported workbook file format")
	// ErrWorkbookPassword defined the error message on receiving the incorrect
	// workbook password.
	ErrWorkbookPassword = errors.New("the supplied open workbook password is not correct")
)

// ErrSheetNotExist defined an error of sheet that does not exist.
type ErrSheetNotExist struct {
	SheetName string
}

// Error returns the error message on receiving the non existing sheet name.
func (err ErrSheetNotExist) Error() string {
	return fmt.Sprintf("sheet %s does not exist", err.SheetName)
}

// newAddCommentError defined the error message on the comment already exist in
// the cell.
func newAddCommentError(cell string) error {

View on GitHub (pinned to f2483381fb)

Solutions

1. Verify the file is a genuine Excel workbook (encrypted or not) and not renamed/misgenerated
2. Re-obtain or re-save the file from its source
3. If the file is truly encrypted, decrypt it fully with the producing tool before opening

Example fix

// before
f, err := OpenReader(brokenReader) // EncryptedPackage too short
// after
buf, _ := io.ReadAll(src)
if len(buf) < 1024 { return errors.New("file truncated") }
f, err := OpenReader(bytes.NewReader(buf))

data, _ := io.ReadAll(r)
if len(data) < 1024 { return errors.New("encrypted package too small / truncated") }

func isCompoundFile(b []byte) bool {
	return len(b) > 8 && bytes.Equal(b[:8], []byte{0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1})
}

f, err := excelize.OpenReader(r)
if errors.Is(err, excelize.ErrWorkbookFileFormat) {
	return fmt.Errorf("file is not a valid encrypted workbook package")
}

When it happens

Trigger: OpenReader/OpenFile on an encrypted OLE compound file with an empty or undersized EncryptedPackage stream (test builds compoundFile with EncryptionInfo but empty package); truncated encrypted files.

Common situations: Opening a non-workbook file renamed to .xlsx that is also a compound file; corrupted download; file encrypted by a tool writing incomplete streams.

Related errors

• ErrUnknownEncryptMechanism
• unsupported image extension
• ErrPasswordLengthInvalid
• ErrUnsupportedEncryptMechanism
• fill type value must be one of 'gradient' or 'pattern'

AI-assisted analysis of qax-os/excelize@f2483381fb (2026-09-02). Data as JSON: /api/errors/3325674f47051908. Report an issue: GitHub.