litedb-org/LiteDB · error · ArgumentNullException

commandReader

Error message

commandReader

What it means

ArgumentNullException thrown by LiteDatabase.Execute(TextReader commandReader, BsonDocument parameters) when commandReader is null. The overload builds a Tokenizer over the reader and then a SqlParser, so a null reader cannot be tokenized and is rejected up front.

Source

Thrown at LiteDB/Client/Database/LiteDatabase.cs:247

        /// </summary>
        public bool RenameCollection(string oldName, string newName)
        {
            if (oldName.IsNullOrWhiteSpace()) throw new ArgumentNullException(nameof(oldName));
            if (newName.IsNullOrWhiteSpace()) throw new ArgumentNullException(nameof(newName));

            return _engine.RenameCollection(oldName, newName);
        }

        #endregion

        #region Execute SQL

        /// <summary>
        /// Execute SQL commands and return as data reader.
        /// </summary>
        public IBsonDataReader Execute(TextReader commandReader, BsonDocument parameters = null)
        {
            if (commandReader == null) throw new ArgumentNullException(nameof(commandReader));

            var tokenizer = new Tokenizer(commandReader);
            var sql = new SqlParser(_engine, tokenizer, parameters);
            var reader = sql.Execute();

            return reader;
        }

        /// <summary>
        /// Execute SQL commands and return as data reader
        /// </summary>
        public IBsonDataReader Execute(string command, BsonDocument parameters = null)
        {
            if (command == null) throw new ArgumentNullException(nameof(command));

            var tokenizer = new Tokenizer(command);
            var sql = new SqlParser(_engine, tokenizer, parameters);
            var reader = sql.Execute();

View on GitHub (pinned to f906a5f850)

Solutions

1. Pass a valid TextReader, e.g. db.Execute(new StringReader(sql)) or db.Execute(new StreamReader(file)).
2. If you have a plain string, use the string overload db.Execute(sql).
3. Null-check the reader source (file/stream) and fail with a clear message before calling Execute.

Example fix

// before
db.Execute((TextReader)null);

// after
db.Execute(new StringReader("SELECT * FROM customers"));
// or for a string
db.Execute("SELECT * FROM customers");

if (commandReader == null) throw new ArgumentNullException(nameof(commandReader));
var reader = db.Execute(commandReader);

static bool IsUsableReader(TextReader r) => r != null;

When it happens

Trigger: Calling db.Execute((TextReader)null); a stream/file that failed to open being passed as null; a multi-statement execution path where the reader was not constructed.

Common situations: File-open failure returning null instead of throwing; helper that builds a reader from a possibly-null stream; confusing the TextReader overload with the string overload and passing null.

Related errors

• command
• connectionString
• stream
• engine
• name

AI-assisted analysis of litedb-org/LiteDB@f906a5f850 (2026-08-13). Data as JSON: /api/errors/3b395098b1f89be3. Report an issue: GitHub.