cefsharp/CefSharp · error · ArgumentNullException

Please provide a valid array

Error message

Please provide a valid array

What it means

Thrown by the ByteArrayResourceHandler constructor when the data byte array is null. The handler exists to serve a byte array to CEF; a null array leaves it nothing to stream, so the constructor rejects it immediately with an ArgumentNullException.

Source

Thrown at CefSharp/Internals/ByteArrayResourceHandler.cs:43

        /// Gets or sets the Mime Type.
        /// </summary>
        public string MimeType { get; set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="ByteArrayResourceHandler"/> class.
        /// </summary>
        /// <param name="mimeType">mimeType</param>
        /// <param name="data">byte array</param>
        public ByteArrayResourceHandler(string mimeType, byte[] data)
        {
            if (string.IsNullOrEmpty(mimeType))
            {
                throw new ArgumentNullException("mimeType", "Please provide a valid mimeType");
            }

            if (data == null)
            {
                throw new ArgumentNullException("data", "Please provide a valid array");
            }

            if (data.Length == 0)
            {
                throw new Exception("Unable to load byte[] with length 0.");
            }

            MimeType = mimeType;
            Data = data;
        }

        bool IResourceHandler.ProcessRequest(IRequest request, ICallback callback)
        {
            //Should never be called
            throw new NotImplementedException("This method should never be called");
        }

        void IResourceHandler.GetResponseHeaders(IResponse response, out long responseLength, out string redirectUrl)

View on GitHub (pinned to 16bc6e0711)

Solutions

1. Ensure the byte array is populated before constructing the handler, e.g. Encoding.UTF8.GetBytes(content).
2. If the data source can legitimately be empty, guard upstream and skip creating the handler or supply a fallback body.
3. Return a different resource handler or null from GetResourceHandler when no data is available instead of forcing construction.

Example fix

// before
var bytes = content != null ? Encoding.UTF8.GetBytes(content) : null;
return new ByteArrayResourceHandler("text/html", bytes);

// after
if (content == null) return null;
var bytes = Encoding.UTF8.GetBytes(content);
return new ByteArrayResourceHandler("text/html", bytes);

if (data == null)
{
    return null; // or throw a clearer domain exception upstream
}
return new ByteArrayResourceHandler(mimeType, data);

static bool HasByteArrayData(byte[] data) => data != null && data.Length > 0;

When it happens

Trigger: Constructing new ByteArrayResourceHandler("text/html", null) or passing a byte array reference that was never populated (e.g. result of a failed/empty download, a deserialization that returned null, an Encoding.GetBytes on a null string).

Common situations: Generating content from a string where the source string was null; reading bytes from a stream that returned null on error; a placeholder/uninitialized field passed into the handler before data is loaded.

Related errors

• Please provide a valid filePath
• Please provide a valid mimeType
• Unable to load byte[] with length 0.
• manager
• Please provide a valid mimeType

AI-assisted analysis of cefsharp/CefSharp@16bc6e0711 (2026-08-13). Data as JSON: /api/errors/1f0868119c5c8858. Report an issue: GitHub.