Office Add-in Yeoman Setup: Node Version Errors and Office.js API Failures

Question

I used the Microsoft documentation for the Yeoman generator to create and debug an Office Add-in for Word on the web: Yeoman Generator for Office Add-ins.

Initially, I encountered multiple dependency and package-version errors related to Node.js modules. I was able to resolve them by downgrading my Node.js version. After that, I ran the following command from Command Prompt:

npm run start -- web --document {MY_WORD_URL}

The Word document opens successfully in Word on the web, and the development certificates are valid and up to date. However, the add-in does not load automatically in the opened document.

As a workaround, I manually uploaded the manifest file through the Add-ins menu in Word on the web, after which the add-in loaded successfully. My main requirement is to save or retrieve the current Word document from within the add-in. However, when I call the Office.context.document.getFileAsync() method, it does not return the Word file and instead throws an error.

I need help understanding why the add-in is not being automatically loaded when launching Word on the web, and why getFileAsync() fails even after the add-in is manually loaded.

Answer 1

Hi @Faizan Mohammed,

I hope I can share some useful information based on my understanding and experience. Below are my thoughts regarding the two questions you raised:

1/Why the add-in does not automatically sideload in Word on the web

Automatic sideloading is the intended behavior of: npm run start -- web --document {url}

On the first run, Word on the web should prompt you to enable Developer Mode and allow the local manifest to be registered. If the command-line process does not successfully sideload the add-in, Microsoft explicitly recommends manually uploading the manifest as the supported fallback: Microsoft Learn: Sideload Office Add-ins to Office on the web

For Office on the web, the sideloaded manifest registration is stored in the browser’s local storage, so clearing the browser cache or switching to another browser requires the add-in to be sideloaded again. A different browser profile may have the same effect because browser profiles typically use separate storage.

It is therefore worth checking whether the command opened the intended browser profile, whether Word is signed in with the expected account, and whether the Developer Mode and manifest-registration prompts were accepted on the first run. The terminal output should also be reviewed for any errors during the manifest-registration step.

Uploading the manifest manually through Home > Add-ins > More Add-ins > Upload My Add-in is a valid Microsoft-documented workaround. It achieves the same practical result of making the add-in available for testing in Word on the web.Without the terminal output, it is difficult to identify exactly why automatic sideloading did not complete. However, since the add-in loads successfully after the manifest is uploaded manually, the manifest and the locally hosted add-in application appear to be generally functional. This suggests that the issue is more likely limited to the automatic sideloading or manifest-registration process.

2/Why getFileAsync() fails even after the add-in is manually loaded

Manually uploading the manifest only makes the add-in available in Word on the web. It does not change the document-access permissions declared in the manifest or resolve an Office.js, document-access, or Word Online service issue. Therefore, successful sideloading does not necessarily mean that getFileAsync() will succeed.

getFileAsync() is supported in Word on the web. When used with Office.FileType.Compressed, it returns the current document in compressed OOXML format as file slices. The manifest must also grant sufficient document access. For an add-in-only XML manifest, Microsoft’s whole-document example uses the ReadWriteDocument permission: Get the whole document from an add-in for PowerPoint or Word - Office Add-ins | Microsoft Learn

The exact cause cannot be determined without the complete error returned by getFileAsync(), particularly its code, name, and message. It would also be helpful to test the same add-in and document in Word desktop:

• If the call fails in both Word desktop and Word on the web, the manifest permissions and implementation should be reviewed first.
• If it works in Word desktop but consistently fails only in Word on the web, perform a hard refresh, test with more than one document and browser, and capture the complete error details.

If the error is 11001, “A network problem has prevented retrieval of the file,” it resembles Word Online regressions reported in June 2026 for documents stored in OneDrive and SharePoint.

OfficeDev/office-js issue #6747: SharePoint Online

OfficeDev/office-js issue #6748: OneDrive and Word Online

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However, Microsoft rolled back the responsible change on June 8, 2026, marked the issues as fixed, and affected developers confirmed that the API was working again. Those issues may be referenced as previous examples, but they should not be presented as an active known issue.

If the web-only failure remains reproducible after a hard refresh and across multiple documents and browsers, I would recommend opening a Microsoft 365 support ticket for service-side investigation. Include the complete error object, Word web build, browser version, document storage location such as OneDrive or SharePoint, account type, reproduction steps, manifest type and permissions, and the result of the Word desktop comparison.

A minimal reproducible sample may also be reported through the OfficeDev/office-js GitHub repository. Without the exact error details, however, it would be premature to conclude that the current failure is the same Word Online regression.

As this is a user-to-user support forum and I am simply a fellow user, I hope the information I've shared provides some useful context based on my research and experience. If possible, I would still recommend working directly with Microsoft Support, as they will be able to provide the most authoritative guidance for your specific situation.

Thank you for taking the time to read my reply and consider my suggestions. I truly appreciate it.

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