Unable to deploy a seemingly-valid manifest.xml for an Outlook side-loading plugin

Question

Hey all,

I have the attached manifest.xml, but I cannot deploy it to any M365 tenants. It passes all validations checks (including npx command line validation AND initial upload at https://admin.cloud.microsoft/#/Settings/IntegratedApps).

Can anyone provide any guidance on how to figure out what is wrong with our manifest.xml please?

Thanks,

<Removed PII>

Answer 1

Hi @tevfikzgrzgven,

Welcome to Microsoft Q&A, and thank you very much for reaching out.

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Based on your description, I reviewed the manifest.xml you shared. Unfortunately, I’m not able to identify any clear issues with the file itself. As a forum moderator, my testing environment is limited, so I can only assist using publicly available documentation and community‑reported behaviors.

That said, you may try the following suggestions to help narrow down the cause:

Test on another tenant:

Some users have reported that when this error occurs, the same manifest successfully deploys on a different Microsoft 365 tenant.

If you can test it on another tenant and it works there, it strongly suggests the issue is backend‑related rather than a problem in your manifest.

Verify icon sizes:

Centralized Deployment is strict about icon dimensions. Please make sure your icons are exactly:

16 × 16 px

32 × 32 px

80 × 80 px

Incorrect icon sizes have caused deployment failures for other users even when validation succeeded.

Double‑check VersionOverrides structure:

Ensure that your manifest nested VersionOverrides 1.1 within VersionOverrides 1.0, and importantly, 1.0 contained no other child elements. Schema structure issues can cause silent failures during deployment.

If the problem persists, I suggest posting it on the OfficeDev GitHub repository, where other developers and product team members can review the manifest more deeply.

You may also consider opening a support request through the Microsoft 365 admin center, where Microsoft can check backend logs directly.

Thank you for understanding.

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