OrchardCMS/OrchardCore · error · Error

is not supported.

Error message

${responseType} is not supported.

What it means

The browser FetchHttpClient's deserializeContent helper throws when the requested responseType is one of the browser-unsupported values 'blob', 'document', or 'json'. In browsers, fetch's streaming/text-based handling only supports 'arraybuffer' and 'text' for SignalR transports, so the client rejects other types eagerly.

Solutions

1. Use `responseType: 'text'` or `'arraybuffer'` in browser code and parse manually (`JSON.parse(await response.text())`)
2. Only use blob/document/json response types with the Node fetch implementation
3. Route raw HTTP API calls through plain fetch/axios instead of the SignalR Http client

Example fix

// before
const request = new HttpRequest('POST', url, body, { responseType: 'json' }); // browser: throws
// after
const request = new HttpRequest('POST', url, body, { responseType: 'text' });
const data = JSON.parse(await httpClient.send(request).then(r => r.content));

const allowed = ['text','arraybuffer']; if (request.responseType && !allowed.includes(request.responseType) && isBrowser) throw new Error('Unsupported responseType in browser');

const isBrowserSafeResponseType = (t) => t === undefined || t === 'text' || t === 'arraybuffer';

try { await client.send(request); } catch (e) { if (/is not supported/.test(e.message)) { request.responseType = 'text'; await client.send(request); } }

When it happens

Trigger: Passing `responseType: 'blob' | 'document' | 'json'` in an HttpRequest sent through the fetch transport in a browser environment; custom code reusing FetchHttpClient for non-SignalR requests with those response types.

Common situations: Copying Node-style SignalR request options to a browser bundle; custom logging/interceptor transport that sets responseType 'json' for convenience; running the same transport code across Node (supported) and browser (unsupported).

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• No method defined.
• No url defined.
• The type ' ' is not support by Azure AI Search
• The specified grant type is not supported.
• The ' ' argument is required.

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/3434779fc3d409cb. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.SignalR/wwwroot/Scripts/signalr.js:704

            // @ts-ignore: unused variable
            this._jar.getCookies(url, (e, c) => cookies = c.join("; "));
        }
        return cookies;
    }
}
function deserializeContent(response, responseType) {
    let content;
    switch (responseType) {
        case "arraybuffer":
            content = response.arrayBuffer();
            break;
        case "text":
            content = response.text();
            break;
        case "blob":
        case "document":
        case "json":
            throw new Error(`${responseType} is not supported.`);
        default:
            content = response.text();
            break;
    }
    return content;
}

;// CONCATENATED MODULE: ./src/XhrHttpClient.ts
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.




class XhrHttpClient extends HttpClient {
    constructor(logger) {
        super();
        this._logger = logger;

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