Getting error when adding Add-ins in Excel

Because the same error happens in both Excel Desktop and Excel for the Web, it is unlikely that the problem is caused by one specific add-in. The message:

“We couldn't connect to the '{0}' catalog server for this add-in”

usually means Excel cannot reach the Microsoft add-in catalog service or there is an account, browser, or network connection issue.

Please try the following steps in order:

Check your Microsoft 365 account

Open Excel:

File → Account

Confirm that:

• You are signed in with the correct Microsoft account
• Your Microsoft 365 Personal subscription is active
• There are no subscription or payment issues

Then sign out of Office completely and sign in again. 

Test the add-in store in your browser

Open a private browser window:

• Edge: InPrivate
• Chrome: Incognito

Sign in with the same Microsoft account and open the Office add-in store:

Microsoft AppSource Office Add-ins

If the store does not open or you cannot view add-ins there, the issue is most likely related to your account or network connection.

Check Excel privacy settings

In Excel Desktop:

File → Account → Account Privacy → Manage Settings

Make sure that connected experiences are enabled.

Office add-ins require these services to work.

Try another network

If possible, test Excel using another internet connection (for example, a mobile hotspot).

• If it works on another network, something on your current network may be blocking Microsoft services.
• If it still fails, the problem is more likely related to your Microsoft account or Microsoft services.

Update Office

Make sure Microsoft 365 is up to date:

Excel → File → Account → Update Options → Update Now

Also ensure Windows updates are installed.

If the problem continues

Please provide...

• Your Microsoft account type (Microsoft 365 Personal, Family, etc.)
• The exact time the error occurred (including your time zone)
• A screenshot of the error
• Whether the problem happens in both Excel Desktop and Excel for the Web
• Whether the AppSource add-in store opens successfully

An Office repair/reinstall is usually not the first solution in this case, because the problem also occurs in Excel for the Web.

I hope this helps narrow down the cause.

The most important first tests are:

1. Confirm the Microsoft 365 subscription/account
2. Test the add-in store in a private browser window
3. Try another network connection

These three steps usually identify where the problem is coming from.