Office Settings & Configuration

How to Fix an Invalid Office Add-in Manifest in Microsoft 365 Admin Center

Emma Brown Oct 22, 2026 869 views

Question details

The user needs to resolve an issue where an Office add-in manifest is rejected as invalid during upload in the Microsoft 365 admin center, despite functioning properly in Excel for the web.

Product: Microsoft 365 Admin Center
Device & OS: not provided
Scenario: Deploying a custom or third-party Office Add-in across an organization using the Microsoft 365 Admin Center.
Observed behavior: The admin center rejects the uploaded XML manifest file as invalid, blocking the deployment process.

Before you start

Ensure you have the latest version of your manifest XML file saved locally, a suitable XML or code editor installed, and administrator privileges to deploy apps in the Microsoft 365 admin center.

Solution 1Recommended

Validate and Correct the XML Manifest

Check the XML manifest file against Microsoft's strict deployment schema to identify and correct missing attributes, unsupported permissions, or incorrect URL formats.

While Excel for the web allows sideloading with looser validation for testing purposes, the Microsoft 365 Admin Center strictly enforces the Office Add-in schema requirements. Any minor discrepancy in the XML structure will cause the upload to fail.

Open the manifest in a code editor

Right-click your XML manifest file and open it in a code editor like VS Code or Notepad to view the underlying code structure.

Check URLs and domains

Scan through the manifest to verify that all SourceLocation URLs, icon paths, and AppDomains explicitly use 'https://' rather than 'http://'.

Verify add-in IDs and versioning

Ensure that the <Id> tag contains a valid, uniquely generated GUID and that the <Version> tag follows the correct numbering format (e.g., 1.0.0.0).

Re-upload to the Admin Center

Save your corrected XML file. Log back into the Microsoft 365 admin center, navigate to Settings > Integrated apps, and try uploading the custom app manifest again.

Automated Validation Tools: If you used the Yeoman generator to build your add-in, you can run the command 'npm run validate' in your project terminal to automatically catch schema errors before uploading.

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Frequently Asked Questions

Why does my add-in manifest work in Excel for the web but not in the Admin Center?

Excel for the web allows basic sideloading for developer testing, which has relaxed validation rules. The Microsoft 365 Admin Center requires strict compliance with the official XML schema and deployment requirements to ensure organizational security and stability.

What are the most common errors in an Office add-in manifest?

The most frequent causes of invalid manifests include using HTTP instead of HTTPS for resource URLs, missing required tags like high-resolution icons, improperly formatted GUIDs, or requesting permissions that conflict with the add-in type.

Can I test my manifest validation online?

Yes, Microsoft provides online schema validation guidance, and developers can use XML validation tools to check their manifest against the official Office Add-ins XSD schema before attempting an admin center upload.

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