iOfficeAI/OfficeCLI · warning · JsonException

Expected property name

Error message

Expected property name

What it means

JsonException from LenientStringDictionaryConverter.Read inside the OBJECT branch: after reading a value and looping, the next token was not a PropertyName (e.g. a value token appeared where a property name was expected). This indicates a structurally malformed props object, not a value-type problem.

Source

Thrown at src/officecli/BatchTypes.cs:41

        {
            while (reader.Read())
            {
                if (reader.TokenType == JsonTokenType.EndArray) return dict;
                if (reader.TokenType != JsonTokenType.String)
                    throw new JsonException("Expected \"key=value\" string in props array");
                var kv = reader.GetString()!;
                var eq = kv.IndexOf('=');
                if (eq > 0) dict[kv[..eq]] = kv[(eq + 1)..];  // skip malformed, as ParseProps does
            }
            throw new JsonException("Unexpected end of JSON");
        }
        if (reader.TokenType != JsonTokenType.StartObject)
            throw new JsonException("Expected object or [\"key=value\"] array for props");
        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndObject) return dict;
            if (reader.TokenType != JsonTokenType.PropertyName)
                throw new JsonException("Expected property name");
            var key = reader.GetString()!;
            reader.Read();
            var value = reader.TokenType switch
            {
                JsonTokenType.String => reader.GetString()!,
                JsonTokenType.Number => reader.TryGetInt64(out var l) ? l.ToString() : reader.GetDouble().ToString(),
                JsonTokenType.True => "true",
                JsonTokenType.False => "false",
                JsonTokenType.Null => "",
                _ => throw new JsonException($"Unexpected token {reader.TokenType} for prop value '{key}'")
            };
            dict[key] = value;
        }
        throw new JsonException("Unexpected end of JSON");
    }

    public override void Write(Utf8JsonWriter writer, Dictionary<string, string> value, JsonSerializerOptions options)
    {

View on GitHub (pinned to 1ced45e900)

Solutions

1. Re-emit props with a real JSON serializer so key/value pairing is guaranteed.
2. Run the full batch through a JSON validator/linter before sending.
3. Confirm every props entry is "key": value, comma-separated.

Example fix

// before: props: { "text": "hi" "count" }   // malformed (missing value)
// after:  props: { "text": "hi", "count": "3" }

// Structural pre-check: every props entry must be a string scalar value
function wellFormedPropsObject(p) {
  if (p == null || typeof p !== 'object' || Array.isArray(p)) return false;
  return Object.entries(p).every(([k, v]) => typeof k === 'string' && ['string','number','boolean'].includes(typeof v));
}

When it happens

Trigger: A props object like {"a":1 2} (a number where the next key should be), {"a":"b" "c"} (two strings in a row), or any object whose key/value pairing is broken.

Common situations: Hand-edited or templated JSON with a missing key or extra value; a serializer bug that emitted values back-to-back.

Related errors

• Expected "key=value" string in props array
• Unexpected end of JSON
• Expected object or ["key=value"] array for props
• Unexpected token {reader.TokenType} for prop value '{key}'
• Expected PropertyName

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/d4fe8e1a06695dbf. Report an issue: GitHub.