Foundry376/Mailspring · error

${action.templateKey} is not a supported action.

Error message

${action.templateKey} is not a supported action.

What it means

Guard in _applyRuleToMessage: a rule action's templateKey is not present in the supported action template map (Actions loaded from the ActionTemplates registry). Occurs when a rule was created by an older/newer Mailspring version or a plugin that defined actions that no longer exist, or the stored rule data is corrupt.

Source

Thrown at app/src/mail-rules-processor.ts:239

    const templateMap = this._getConditionTemplateMap();
    return fn.call(rule.conditions, (condition) => {
      const template = templateMap.get(condition.templateKey);
      if (!template) {
        console.warn(`Unknown mail rule condition template: ${condition.templateKey}`);
        return false;
      }
      const value = template.valueForMessage(message);
      return template.evaluate(condition, value);
    });
  }

  async _applyRuleToMessage(rule: MailRule, message: Message, thread: Thread) {
    try {
      const actionPromises = rule.actions.map((action) => {
        const actionFn = MailRulesActions[action.templateKey];
        if (!actionFn) {
          throw new Error(`${action.templateKey} is not a supported action.`);
        }
        return actionFn(message, thread, action.value);
      });

      const actionResults = await Promise.all<Task | undefined>(actionPromises);
      const actionTasks = actionResults.filter((r) => r instanceof Task);

      // mark that none of these tasks are undoable
      actionTasks.forEach((t) => {
        (t as any).canBeUndone = false;
      });

      const performLocalPromises = actionTasks.map((t) => TaskQueue.waitForPerformLocal(t));
      Actions.queueTasks(actionTasks);
      await performLocalPromises;
    } catch (err) {
      // Errors can occur if a mail rule specifies an invalid label or folder, etc.
      // Disable the rule. Disable the mail rule so the failure is reflected in the

View on GitHub (pinned to 648c685d60)

Solutions

1. Open the rule in Preferences > Mail Rules and re-pick the action
2. Update Mailspring to a version that supports the action
3. Delete the obsolete rule; the error aborts processing of this message by the rule

When it happens

Trigger: Thrown at app/src/mail-rules-processor.ts:239 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Foundry376/Mailspring@648c685d60 (2026-09-03). Data as JSON: /api/errors/0f5344417e943d08. Report an issue: GitHub.