MonoGame/MonoGame · error · ContentLoadException

Resource is not in binary format

Error message

Resource is not in binary format

What it means

After fetching the resource object, OpenStream requires it be a byte[] (the raw XNB binary). If the object exists but is not a byte array (e.g. a string, Bitmap, or typed object), MonoGame throws ContentLoadException("Resource is not in binary format"). The resource must contain the serialized XNB bytes, not a typed value.

Source

Thrown at MonoGame.Framework/Content/ResourceContentManager.cs:52

        /// <summary>
        /// Opens a stream for reading the specified resource.
        /// Derived classes can replace this to implement pack files or asset compression.
        /// </summary>
        /// <param name="assetName">The name of the asset being read.</param>
        /// <exception cref="ContentLoadException">
        /// Error loading <paramref name="assetName"/>.
        /// The resource was not a binary resource, or the resource was not found.
        /// </exception>
        protected override System.IO.Stream OpenStream(string assetName)
        {
            object obj = this.resource.GetObject(assetName);
            if (obj == null)
            {
                throw new ContentLoadException("Resource not found");
            }
            if (!(obj is byte[]))
            {
                throw new ContentLoadException("Resource is not in binary format");
            }
            return new MemoryStream(obj as byte[]);
        }
    }
}

View on GitHub (pinned to 1d71bbd0ff)

Solutions

1. Embed the asset as a binary XNB byte[] resource (the raw .xnb file bytes).
2. Re-export resources so each asset is a byte[] entry, not a typed object.
3. Verify with ResourceManager.GetObject that the value is a byte[] before loading.

Example fix

// before: .resx holds 'Font' as a System.Drawing.Bitmap -> throws 272
var font = Content.Load<SpriteFont>("Font");

// after: embed the compiled .xnb file as a byte[] resource named 'Font'
var font = Content.Load<SpriteFont>("Font");

// Verify the resource is a byte[] before letting OpenStream run.
object obj = resourceManager.GetObject(assetName);
if (!(obj is byte[])) return; // not a binary XNB blob

static bool IsBinaryResource(ResourceManager rm, string name) => rm.GetObject(name) is byte[];

try { var tex = Content.Load<Texture2D>("Font"); }
catch (ContentLoadException ex) when (ex.Message == "Resource is not in binary format")
{ /* re-embed the .xnb as a byte[] resource */ }

When it happens

Trigger: The resource key resolves to a non-binary embedded resource (a string, Image, etc.) instead of the raw XNB byte[].

Common situations: .resx embedded the asset as a typed object rather than as a binary XNB blob; wrong resource embedding mode; designer-typed resource overriding the byte stream.

Related errors

• Resource not found
• resource
• The content file was not found.
• The directory was not found.
• Opening stream error.

AI-assisted analysis of MonoGame/MonoGame@1d71bbd0ff (2026-08-13). Data as JSON: /api/errors/899ccbef42d26532. Report an issue: GitHub.