deepseek-ai/deepseek-harness · error · Error

malformed prompt variable reference at "${text.slice(open, o

Error message

malformed prompt variable reference at "${text.slice(open, open + 16)}…" in ${kind} "${input.name}" (references are complete simple {{name}} groups)

What it means

Error "malformed prompt variable reference at "${text.slice(open, open + 16)}…" in ${kind} "${input.name}" (references are complete simple {{name}} groups)" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/system-prompt/src/index.ts:271

    .map(context => ({ name: context.name, text: interpolate(context, assembly.variables, 'context') }))
    .filter(section => section.text.length > 0)
}

/** Interpolate one section or context and attribute diagnostics to its owning input. */
function interpolate(
  input: AssembledSection | AssembledContext,
  variables: Record<string, string | undefined>,
  kind: 'section' | 'context',
): string {
  const text = input.text
  let result = ''
  let last = 0
  for (let open = text.indexOf('{{'); open >= 0; open = text.indexOf('{{', last)) {
    const group = GROUP_AT.exec(text.slice(open))
    if (group === null) {
      // A later closing brace makes this malformed; otherwise it is literal prose.
      if (text.indexOf('}}', open + 2) >= 0) {
        throw new Error(`malformed prompt variable reference at "${text.slice(open, open + 16)}…" in ${kind} "${input.name}" (references are complete simple {{name}} groups)`)
      }
      result += text.slice(last, open + 2)
      last = open + 2
      continue
    }
    // `{{}}` yields an empty name and follows the malformed-reference path.
    const name = group[0].slice(2, -2)
    if (!VARIABLE_NAME.test(name)) {
      throw new Error(`malformed prompt variable reference "{{${name}}}" in ${kind} "${input.name}" (variable names match ${String(VARIABLE_NAME)})`)
    }
    // Do not resolve unregistered names through Object.prototype.
    if (!Object.hasOwn(variables, name)) {
      const known = Object.keys(variables)
      throw new Error(`unknown prompt variable "{{${name}}}" in ${kind} "${input.name}"; registered variables: ${known.length > 0 ? known.join(', ') : '(none)'}`)
    }
    const value = variables[name]
    if (value === undefined) {
      throw new Error(`prompt variable "{{${name}}}" has no value for this assembly (${kind} "${input.name}")`)

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/system-prompt/src/index.ts:271 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/d31f9089fbcc1ed7. Report an issue: GitHub.