What causes "Module value is undefined for module ${module.id}" in windmill-labs/windmill?

Open the flow YAML at the failing module `id` and add back its `value` block (type + content/inputs)

Module value is undefined for module ${module.id}

Error message

Module value is undefined for module ${module.id}

What it means

replaceInlineScripts walks a flow's module tree and, for each module, inlines file contents back into the flow definition before pushing. If `module.value` is undefined — the module has no value payload at all — it throws `Module value is undefined for module <id>`. A well-formed flow module (rawscript, flow, etc.) always carries a value, so this indicates a malformed flow definition or an incomplete/incorrectly-shaped parsed module.

Source

Thrown at cli/windmill-utils-internal/src/inline-scripts/replacer.ts:86

export async function replaceInlineScripts(
    modules: FlowModule[],
    fileReader: (path: string) => Promise<string>,
    logger: {
      info: (message: string) => void,
      error: (message: string) => void,
    } = {
      info: () => {},
      error: () => {},
    },
    localPath: string,
    separator: string = "/",
    removeLocks?: string[],
    missingFiles?: string[],
  ): Promise<string[]> {
    const missing = missingFiles ?? [];
    await Promise.all(modules.map(async (module) => {
      if (!module.value) {
        throw new Error(`Module value is undefined for module ${module.id}`);
      }

      if (module.value.type === "rawscript") {
        await replaceRawscriptInline(
          module.id,
          module.value,
          fileReader,
          logger,
          separator,
          removeLocks,
          missing
        );
      } else if (module.value.type === "forloopflow" || module.value.type === "whileloopflow") {
        await replaceInlineScripts(module.value.modules, fileReader, logger, localPath, separator, removeLocks, missing);
      } else if (module.value.type === "branchall") {
        await Promise.all(module.value.branches.map(async (branch) => {
          await replaceInlineScripts(branch.modules, fileReader, logger, localPath, separator, removeLocks, missing);
        }));

View on GitHub (pinned to e474e8803c)

Solutions

Open the flow YAML at the failing module `id` and add back its `value` block (type + content/inputs)
Restore the flow file from git (`git checkout -- <file>`) to recover the missing value
Re-pull the flow with `wmill sync pull` so the definition is rebuilt from the backend
If generating flows in code, ensure every module gets a non-null `value` before calling replaceInlineScripts

Example fix

// before
{
  "id": "a",
  "value": undefined // module missing value
}

// after
{
  "id": "a",
  "value": { "type": "rawscript", "content": "...", "language": "python3" }
}

Defensive patterns

Strategy: type-guard

Validate before calling

interface FlowModuleLike { id: string; value?: unknown }
function allModulesHaveValue(modules: FlowModuleLike[]): boolean {
  return modules.every(m => m.value != null);
}
if (!allModulesHaveValue(flow.value.modules)) throw new Error('Flow has modules without value');

Type guard

function hasModuleValue(m: { id: string; value?: unknown }): m is { id: string; value: object } {
  return m.value != null && typeof m.value === 'object';
}

Try / catch

try {
  await replaceInlineScripts(flow.value.modules, ...);
} catch (e) {
  if ((e as Error).message.startsWith('Module value is undefined')) {
    console.error('Flow definition malformed — restore from git or re-pull');
  } else throw e;
}

Prevention

Validate flow YAML shape (every module has id + value) before pushing
Never resolve merge conflicts by deleting a module's value block
Type generated flow objects so a missing value is a compile-time error

When it happens

Trigger: replaceInlineScripts called on modules from a flow YAML where a module entry lacks its `value` key (e.g. hand-edited flow file, a module type the parser did not resolve, or a flow/suspend branch whose value was stripped by tooling).

Common situations: Manually editing a flow YAML and deleting or renaming the `value` block; a merge conflict resolved by dropping a module's value; generating flows programmatically with a missing value for some module id; version skew where an old flow format lacks value on a new module type.

Related errors

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/7815e7c281282992. Report an issue: GitHub.