qax-os/excelize · error

fill pattern value must be between 0 and 18

Error message

fill pattern value must be between 0 and 18

What it means

ErrFillPattern is returned by parseFormatStyleSet when Fill.Type is "pattern" and Fill.Pattern is outside the inclusive range 0-18. The pattern value selects which OOXML pattern style (solid, dots, stripes, etc.) to apply.

Source

Thrown at errors.go:77

	// ErrExistsSheet defined the error message on given sheet already exists.
	ErrExistsSheet = errors.New("the same name sheet already exists")
	// ErrExistsTableName defined the error message on given table already
	// exists.
	ErrExistsTableName = errors.New("the same name table already exists")
	// ErrFillType defined the error message on receive an invalid fill type.
	ErrFillType = errors.New("fill type value must be one of 'gradient' or 'pattern'")
	// ErrFillGradientColor defined the error message on receive an invalid fill
	// color for 'gradient' type.
	ErrFillGradientColor = errors.New("fill color value must be an array of two colors for 'gradient' type")
	// ErrFillGradientShading defined the error message on receive an invalid
	// fill shading for 'gradient' type.
	ErrFillGradientShading = errors.New("fill shading value must be between 0 and 16 for 'gradient' type")
	// ErrFillPatternColor defined the error message on receive an invalid fill
	// color for 'pattern' type.
	ErrFillPatternColor = errors.New("fill color value must be empty or an array of one color for 'pattern' type")
	// ErrFillPattern defined the error message on receive an invalid fill
	// pattern.
	ErrFillPattern = errors.New("fill pattern value must be between 0 and 18")
	// ErrFontLength defined the error message on the length of the font
	// family name overflow.
	ErrFontLength = fmt.Errorf("the length of the font family name must be less than or equal to %d", MaxFontFamilyLength)
	// ErrFontSize defined the error message on the size of the font is invalid.
	ErrFontSize = fmt.Errorf("font size must be an integer from %d to %d points", MinFontSize, MaxFontSize)
	// ErrFormControlValue defined the error message for receiving a scroll
	// value exceeds limit.
	ErrFormControlValue = fmt.Errorf("scroll value must be an integer from 0 to %d", MaxFormControlValue)
	// ErrGroupSheets defined the error message on group sheets.
	ErrGroupSheets = errors.New("group worksheet must contain an active worksheet")
	// ErrImgExt defined the error message on receive an unsupported image
	// extension.
	ErrImgExt = errors.New("unsupported image extension")
	// ErrInvalidFormula defined the error message on receive an invalid
	// formula.
	ErrInvalidFormula = errors.New("formula not valid")
	// ErrMaxFilePathLength defined the error message on receive the file path
	// length overflow.

View on GitHub (pinned to f2483381fb)

Solutions

1. Set Fill.Pattern to an integer between 0 and 18 inclusive (1 is the solid pattern).
2. Clamp the value to [0, 18] before calling NewStyle.
3. Map your pattern names to this library's 0-18 numbering explicitly.

Example fix

// before
f.NewStyle(&Style{Fill: Fill{Type: "pattern", Pattern: 19}})
// after
f.NewStyle(&Style{Fill: Fill{Type: "pattern", Pattern: 1}}) // 1 = solid

if fill.Type == "pattern" && (fill.Pattern < 0 || fill.Pattern > 18) {
    return fmt.Errorf("pattern %d out of range 0-18", fill.Pattern)
}

func validPattern(p int) bool { return p >= 0 && p <= 18 }

_, err := f.NewStyle(&Style{Fill: fill})
if errors.Is(err, excelize.ErrFillPattern) {
    fill.Pattern = 1 // default to solid
    _, err = f.NewStyle(&Style{Fill: fill})
}

When it happens

Trigger: Calling f.NewStyle(&Style{Fill: Fill{Type: "pattern", Pattern: 19}}) or passing a negative Pattern value.

Common situations: Using pattern constants from another library or a newer OOXML spec revision, computing pattern from user input, or off-by-one errors against the 0-18 valid range.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• fill color value must be empty or an array of one color for
• fill type value must be one of 'gradient' or 'pattern'
• fill color value must be an array of two colors for 'gradien
• fill shading value must be between 0 and 16 for 'gradient' t
• group worksheet must contain an active worksheet

AI-assisted analysis of qax-os/excelize@f2483381fb (2026-09-02). Data as JSON: /api/errors/434da3b10e1baa48. Report an issue: GitHub.