Add-In Catalog Server Error (mostly on Web & Mac)

Question

We did not make any updates to our Add-In (published through Office Store) in 6 months while all of a sudden dozens of users reported that they are "Unable to Connect to the Office Store Catalog server for this add-in".

We have been documenting that this only happens to some users in various organizations, they are mostly on Web and Mac and appears that they cannot install ANY Add-Ins. Some of these users had the Add-In installed for months, some tried for the first time. We also tried for them to go to File > Info > Privacy Settings > Check the box for permissions that would allow them to install the Add-In but that did not work.

Some of them have an IT department but some are just on a one person Microsoft account.

We welcome any suggestions.

Answer 1

DearFranziska Ibscher,

Thank you for reaching out and reporting the issue related to our Office Store Add-In. We’d like to share a detailed troubleshooting guide to help resolve the “Unable to Connect to the Office Store Catalog server for this add-in” error, especially on Mac and Office Online (Web) platforms.

1. Check Privacy Settings

• On Mac: Go to Excel/Word > Preferences > Privacy, and enable “Optional connected experiences”.
• On Web: Ensure your account is not in a restricted or private mode.
• After enabling, restart the Office app and try installing the Add-In again.

2. Check Network and Firewall Configuration

• Try accessing https://appsource.microsoft.com in a browser. If the site is blocked or shows an error, your network may be restricting access.
• Switch to a different network (e.g., home Wi-Fi or mobile hotspot) to test.
• Temporarily disable any antivirus or internet security software.
• Ensure your system clock is accurate and DNS settings are not overriding Microsoft domains.

3. Re-authenticate Your Office Account

• Sign out of your Office application and sign back in with your Microsoft 365 account.
• This refreshes authentication tokens and may resolve the issue.

4. Update or Roll Back Office Version (Mac)

• Make sure you’re using the latest version of Office for Mac.
• If the issue started after a recent update, consider rolling back to a previous stable version (e.g., from 16.71 to 16.69).

5. Create a New macOS Profile or Reset Office

• If the issue affects only one user account on your Mac, try creating a new macOS user and test the Add-In.
• You may also reset Office by removing credentials from Keychain Access and deleting cached settings under ~/Library/Containers.

6. Check Account Type and Mailbox Configuration

• For organizational accounts, verify whether the mailbox is hosted on-premises or in Exchange Online. Users with on-prem mailboxes may need to migrate to Exchange Online.
• Ensure your account has a valid license that includes Office services.
• If conditional access policies are in place, confirm your device is compliant.

7. Try Office Online or Another Platform

• If Excel on Mac fails to install the Add-In, try using Excel Online or a Windows device as a temporary workaround.

8. Manually Sideload the Add-In (Advanced Users)

• Developers can provide the manifest file for manual installation via the “Upload My Add-In” option in the My Add-ins dialog.
• Note: This method bypasses the Office Store and may have limitations.

If you have any new updates regarding the issue, or if the information we’ve provided hasn’t been effective for your situation, please feel free to share with us. We’re happy to continue investigating and supporting you further.

Best regards,

Ryan-N-MSFT | Microsoft Community Support Specialist

Answer 2

DearFranziska Ibscher,

I hope the information I shared earlier was at least somewhat helpful in addressing your issue. If the previous methods haven’t been effective, please feel free to let me know. I’d be happy to explore the issue more deeply with you so we can work together toward a better solution. 

Thank you very much, and I wish you a great day. 

Best regards, 
Ryan-N-MSFT | Microsoft Community Support Specialist 

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Answer 3

Hi Ryan,

Unfortunately, none of your solutions worked. How can we work together toward a better solution? What are the best next steps?

Thank you in advance.

Answer 4

Hi Franziska,

Thank you for your response. Your feedback is already a form of collaboration with me—by sharing which previous methods didn’t work, you’re helping me narrow down the scope of the issue.

Here are some targeted troubleshooting steps based on your setup:

 For Office on the Web using Mac:

1. Try using a different browser:

Avoid using Safari, as its strict privacy settings may block connections to the Office Store.

1. Clear your browser’s cache and cookies, then restart the browser.
2. Disable any browser extensions, especially ad blockers or tracking protection tools.
3. Make sure third-party cookies are allowed and JavaScript is enabled.

 For Network-related issues:

• Try switching to a different network, such as home Wi-Fi or a mobile hotspot.
• If you're on a corporate or restricted network, it's possible that a firewall or proxy is blocking domains like *.office.com or appsource.microsoft.com. Please check with your IT department if applicable.

Temporary Workaround:

• Try accessing https://appsource.microsoft.com directly in your browser and install the add-in from there (if available).
• Alternatively, using Excel Online on a Windows device may allow the add-in to install without this issue.

If you found the answer helpful, we kindly invite you to mark it as the accepted solution. Once marked, it will automatically be pinned to the top. Since many other users also search for information in this community, your valuable contribution will help them easily find the right channel and useful insights more quickly. 

Thank you very much, and I wish you a great day. 

Best regards, 
Ryan-N-MSFT | Microsoft Community Support Specialist

Answer 5

Hi Franziska,

I’m looking forward to hearing back from you. If you have any new information or updated screenshots related to the issue, I would greatly appreciate it.

Best regards,

Ryan-N-MSFT | Microsoft Community Support Specialist