“SDK not initialized” error?

Question

I’m developing a custom Microsoft Teams tab using the Teams JavaScript SDK. The app loads correctly in a browser, but inside the Teams client it fails with an error indicating that the Teams SDK is not initialized.

The initialization code is in place, but the issue appears intermittently depending on the environment.

Answer 1

Hi Mattison Zhabrea

As far as I know, the intermittent failure of the Teams JavaScript SDK initialization typically stems from a race condition where the application logic attempts to invoke SDK methods before the asynchronous initialization process has reached a completed state.

This behavior is often more pronounced in the Teams Desktop client than in a standard browser due to the specific security and lifecycle management requirements of the embedded WebView2 environment, which requires a strictly sequenced handshake between the tab and the host.

Given this, to address this issue, ensure that the Microsoft Teams SDK is initialized synchronously and as early as possible in your application lifecycle. Specifically, microsoftTeams.app.initialize() (or app.initialize() for SDK v2.x) must be awaited before any other Teams SDK APIs are invoked. All subsequent SDK calls should be gated behind a successful initialization to avoid race conditions or undefined behavior.

In addition, kindly confirm that your manifest.json is correctly configured. All required host URLs and authentication endpoints must be explicitly listed in the validDomains array; otherwise, the Teams host may block the SDK initialization request.

For example:

import * as microsoftTeams from "@microsoft/teams-js";
 
async function runTeamsApp() {
    try {
        await microsoftTeams.app.initialize();
        // It is now safe to call other SDK methods
        const context = await microsoftTeams.app.getContext();
        console.log("App initialized successfully", context);
    } catch (error) {
        console.error("Failed to initialize Teams SDK:", error);
    }
}
 
runTeamsApp();

You can read here for more information:

Teams JavaScript client library

Microsoft 365 app manifest schema reference

Hope my answer will help you.

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