Foundry376/Mailspring · error · Error

Validation failed at ${keyPath}, ${JSON.stringify(value)} mu

Error message

Validation failed at ${keyPath}, ${JSON.stringify(value)} must be an object

What it means

Config schema enforcer for type 'object': the value failed the isPlainObject check (arrays, null, class instances, or primitives all fail), so it cannot be validated against the schema's properties. Fires when a config key declared as an object receives an array or scalar.

Source

Thrown at app/src/config.ts:838

      }
      return value;
    },
  },

  null: {
    // null sort of isnt supported. It will just unset in this case
    coerce(keyPath, value, schema) {
      if (![undefined, null].includes(value)) {
        throw new Error(`Validation failed at ${keyPath}, ${JSON.stringify(value)} must be null`);
      }
      return value;
    },
  },

  object: {
    coerce(keyPath, value, schema) {
      if (!isPlainObject(value)) {
        throw new Error(
          `Validation failed at ${keyPath}, ${JSON.stringify(value)} must be an object`
        );
      }
      if (schema.properties == null) {
        return value;
      }

      const newValue = {};
      for (const prop in value) {
        const propValue = value[prop];
        const childSchema = schema.properties[prop];
        if (childSchema != null) {
          try {
            newValue[prop] = this.executeSchemaEnforcers(
              `${keyPath}.${prop}`,
              propValue,
              childSchema
            );

View on GitHub (pinned to 648c685d60)

Solutions

1. Write a plain JSON object literal at keyPath (arrays are rejected even if intended)
2. Fix hand-edited config.json where braces were dropped or the value became an array

When it happens

Trigger: Thrown at app/src/config.ts:838 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/3dec1e7215e66f97. Report an issue: GitHub.