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.

Because every add-in fails in desktop Excel and Excel for the web, this is unlikely to be one add-in’s defect. The literal “{0}” suggests the catalog response is not rendering correctly. Verify Microsoft 365 is signed in with the Personal account and test the add-in store in a private browser window. In desktop Excel, open File > Account > Account Privacy > Manage Settings and enable connected experiences; Office add-ins depend on them. Update Office, Windows, Edge, and WebView2, then restart. Confirm the date, time, and time zone, and test another network to rule out DNS, proxy, firewall, or filtering interference. If the web error persists across devices and networks, check Microsoft service status and return to support with the UTC test time, account type, screenshots, and failing add-in names. An Online Repair is reasonable only for the desktop client; it cannot fix the failure in Excel for the web.