dotnet/aspnetcore · error · Error

Cannot create a JSStreamReference from the value

Error message

Cannot create a JSStreamReference from the value '${streamReference}'.

What it means

Thrown by DotNet.createJSStreamReference() as a catch-all wrapper when the internal createJSObjectReference() call fails while building the stream reference. Since the stream code has already validated the value is a Blob or typed array, this fallback fires only if the value is somehow not an object/function after those checks (essentially unreachable in normal use).

Solutions

1. Ensure the value passed is a genuine Blob or standard typed array instance, not a proxy or wrapper.
2. Log the value's typeof and constructor before calling createJSStreamReference to diagnose.
3. Reconstruct the data as a plain Uint8Array to bypass any proxying.

Example fix

// before
const ref = createJSStreamReference(new Proxy(new Uint8Array(8), {}));

// after
const ref = createJSStreamReference(new Uint8Array(8));

function isPlainObjectOrTypedArray(v) { return v != null && (v instanceof Blob || v.buffer instanceof ArrayBuffer) && typeof v === 'object'; }

try { return DotNet.createJSStreamReference(value); } catch (e) { throw new Error(`Stream reference creation failed for ${Object.prototype.toString.call(value)}.`, { cause: e }); }

When it happens

Trigger: The Blob/typed-array passed has been mutated or proxied such that createJSObjectReference's typeof check fails; a Symbol or other exotic non-object value slips through; defensive code path for unexpected inputs.

Common situations: Proxy-wrapped typed array whose typeof is not 'object'; a Blob polyfill that returns a non-object; extremely rare in practice — usually indicates a corrupted or non-standard runtime.

Related errors

• Cannot create a JSObjectReference from the value
• Cannot create a JSStreamReference from the value
• JS object instance with Id
• Supplied value is not a typed array or blob.
• Byte array index ' ' does not exist.

AI-assisted analysis of dotnet/aspnetcore@3600ca084e (2026-08-11). Data as JSON: /api/errors/f18c20cc5f081072. Report an issue: GitHub.

Appendix: source

Thrown at src/JSInterop/Microsoft.JSInterop.JS/src/src/Microsoft.JSInterop.ts:219

      } else if (streamReference.buffer instanceof ArrayBuffer) {
          if (streamReference.byteLength === undefined) {
              throw new Error(`Cannot create a JSStreamReference from the value '${streamReference}' as it doesn't have a byteLength.`);
          }

          length = streamReference.byteLength;
      } else {
          throw new Error("Supplied value is not a typed array or blob.");
      }

      const result: any = {
          [jsStreamReferenceLengthKey]: length
      };

      try {
          const jsObjectReference = createJSObjectReference(streamReference);
          result[jsObjectIdKey] = jsObjectReference[jsObjectIdKey];
      } catch (error) {
          throw new Error(`Cannot create a JSStreamReference from the value '${streamReference}'.`);
      }

      return result;
  }

  /**
   * Disposes the given JavaScript object reference.
   *
   * @param jsObjectReference The JavaScript Object reference.
   */
  export function disposeJSObjectReference(jsObjectReference: any): void {
      const id = jsObjectReference && jsObjectReference[jsObjectIdKey];

      if (typeof id === "number" && id !== -1) {
          disposeJSObjectReferenceById(id);
      }
  }

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