gohugoio/hugo · error

there is no such an operation

Error message

there is no such an operation

What it means

DoArithmetic accepts an operator as a rune and only implements '+', '-', '*', and '/'. Any other rune reaches the default case at common/math/math.go:131 and returns this error. In practice user templates can't pass arbitrary operators (add/sub/mul/div hardcode them), so this surfaces mainly from internal or programmatic callers passing an unsupported op.

Source

Thrown at common/math/math.go:131

		return au - bu, nil
	case '*':
		if isInt {
			return ai * bi, nil
		} else if isFloat {
			return af * bf, nil
		}
		return au * bu, nil
	case '/':
		if isInt && bi != 0 {
			return ai / bi, nil
		} else if isFloat && bf != 0 {
			return af / bf, nil
		} else if isUint && bu != 0 {
			return au / bu, nil
		}
		return nil, errors.New("can't divide the value by 0")
	default:
		return nil, errors.New("there is no such an operation")
	}
}

View on GitHub ↗ (pinned to 8a468df065)

Solutions

1. Use one of the supported operators: '+', '-', '*', '/'.
2. For modulo in templates use `mod`/`math.Mod`; for powers use `math.Pow` — DoArithmetic does not implement them.
3. If extending Hugo, add the operator case to the switch in DoArithmetic rather than passing an unhandled rune.

Example fix

// before
res, err := math.DoArithmetic(a, b, '%')
// after
res, err := math.DoArithmetic(a, b, '/') // or use the dedicated mod helpers

validOps := map[rune]bool{'+': true, '-': true, '*': true, '/': true}
if !validOps[op] { /* reject before calling */ }

v, err := math.DoArithmetic(a, b, op)
if err != nil {
	// unknown operator: programming error — fail fast, fix the call site
}

When it happens

Trigger: Calling common/math.DoArithmetic (directly from Go code, a fork, or a custom build) with an op rune other than '+', '-', '*', '/' — e.g. '%' for modulo or '^' for power.

Common situations: Custom Hugo forks or Go code reusing the math package and expecting modulo/power support; modulo in templates must use the separate `mod`/`math.Mod` functions, not DoArithmetic.

Related errors

• errMustTwoNumbersError
• errMustOneNumberError
• the math.Abs function requires a numeric argument
• Ceil operator can't be used with non-float value
• Floor operator can't be used with non-float value

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/e4b32b43c396ef51.json. Report an issue: GitHub ↗.