MSIX Package Upload Stuck at "null Bytes" and "Taking a long time to process"

Harshad B Bhadka 0 Reputation points
2026-02-04T06:10:00.4766667+00:00

Hi everyone,

I am attempting to upload an MSIX package for my Python application to the Microsoft Partner Center, but I am encountering a persistent issue.

Problem Details:

Package Format: MSIX (x64)

File Size: 98 MB

Version: 1.1.1.0

  • Error Message: "The package [FileName].msix is taking a long time to process... [PublisherName].PDFStampSignature_1.1.1.0_x64.msix null Bytes"

Status: The upload bar finishes, but then the file size shows as "null Bytes" and the status remains stuck in "Processing" for hours.

What I have tried so far:

Verified that the Identity Name and Publisher CN in the AppxManifest.xml exactly match my Partner Center dashboard.

Added the runFullTrust capability manually in the manifest.

Signed the package using a self-signed certificate with the correct Publisher CN.

Cleared browser cache and tried uploading via Microsoft Edge (including Incognito mode).

Ensured that only the "Windows 10/11 Desktop" device family is selected (Xbox and others are unchecked).

Despite these steps, the validation never completes. Has anyone faced this "null Bytes" issue with larger MSIX uploads? Is there a specific validation check that might be failing silently behind the scenes?

Any guidance would be greatly appreciated. Hi everyone,

I am attempting to upload an MSIX package for my Python application to the Microsoft Partner Center, but I am encountering a persistent issue.

Problem Details:

Package Format: MSIX (x64)

File Size: 98 MB

Version: 1.1.1.0

  • Error Message: "The package [FileName].msix is taking a long time to process... [PublisherName].PDFStampSignature_1.1.1.0_x64.msix null Bytes"

Status: The upload bar finishes, but then the file size shows as "null Bytes" and the status remains stuck in "Processing" for hours.

What I have tried so far:

Verified that the Identity Name and Publisher CN in the AppxManifest.xml exactly match my Partner Center dashboard.

Added the runFullTrust capability manually in the manifest.

Signed the package using a self-signed certificate with the correct Publisher CN.

Cleared browser cache and tried uploading via Microsoft Edge (including Incognito mode).

Ensured that only the "Windows 10/11 Desktop" device family is selected (Xbox and others are unchecked).

Despite these steps, the validation never completes. Has anyone faced this "null Bytes" issue with larger MSIX uploads? Is there a specific validation check that might be failing silently behind the scenes?

Any guidance would be greatly appreciated.

Microsoft Partner Center API

1 answer

Sort by: Newest
Most helpful Newest Oldest

  1. AI answer

    2026-02-04T06:10:14.8933333+00:00

    It seems you are experiencing an issue with uploading your MSIX package to the Microsoft Partner Center, specifically with the package being stuck at "null Bytes" and taking a long time to process. Here are a few troubleshooting steps you can consider:

    1. Check Package Size: Since your package is 98 MB, ensure that it does not exceed any size limits imposed by the Partner Center. Sometimes larger files may take longer to process or may encounter issues.
    2. Inspect the Manifest: Since you've verified the Identity Name and Publisher CN, ensure that there are no other issues in the AppxManifest.xml. Sometimes, even minor errors can cause validation to fail silently.
    3. Use Valid Certificates: Ensure that the self-signed certificate you are using is valid and properly configured. If possible, try using a certificate from a trusted Certificate Authority (CA) instead of a self-signed one.
    4. Log Files: Check if there are any log files generated during the upload process. These logs can provide insights into what might be going wrong. The logs can usually be found in the local application data directory.
    5. Browser Issues: Since you've already tried clearing the cache and using Incognito mode, consider trying a different browser or device altogether to rule out browser-specific issues.
    6. Contact Support: If the issue persists, consider reaching out to Microsoft support for assistance. They may have more specific insights into the error messages and can provide guidance tailored to your situation.
    7. Retry Uploading: Sometimes, simply retrying the upload after some time can resolve temporary issues with the Partner Center.

    These steps may help you identify the underlying cause of the upload issue.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

    Was this answer helpful?

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.