Microsoft 365 Copilot Service Is Temporarily Unavailable Error: Fix

You see the error message “Microsoft 365 Copilot Service Is Temporarily Unavailable” when you try to open the Copilot pane in Word, Excel, or Outlook. This message appears because the Copilot service endpoint cannot be reached from your client application. The root cause is often a licensing misconfiguration, a network proxy blocking the required URL, or a temporary outage on the Microsoft side. This article explains how to identify the exact cause and apply the correct fix so you can resume using Copilot within minutes.

Why the Copilot Service Unavailable Error Appears

The error “Microsoft 365 Copilot Service Is Temporarily Unavailable” is a client-side message that the Copilot pane displays when it cannot establish a connection to the Copilot backend service. The Microsoft 365 client applications rely on a set of specific URLs and IP ranges to reach the Copilot API. When any of these endpoints are blocked, the client cannot authenticate the user or retrieve grounded responses from Microsoft Graph.

There are three main categories of causes:

License Assignment Issues

Copilot requires a per-user license that is assigned through the Microsoft 365 admin center. If the license is missing, expired, or not properly assigned to the user’s tenant, the client application will reject the service connection. The error message does not always specify a license problem, so this is the first thing to check.

Network or Proxy Restrictions

Corporate networks often use proxy servers or firewalls that inspect HTTPS traffic. If the Copilot endpoints are not on the allowlist, the connection is dropped. The client then shows the “temporarily unavailable” error even though the Microsoft service is running normally. The same problem can occur with VPN configurations that route traffic through restricted gateways.

Microsoft Service Outage

Rarely, the Copilot service itself experiences a regional or global outage. Microsoft publishes these incidents on the Service health dashboard in the admin center. If an active advisory exists, no client-side fix will work until Microsoft resolves the issue.

Steps to Fix the Copilot Service Unavailable Error

Follow these steps in the order listed. Each step addresses one of the root causes. Test Copilot after each step to see if the error clears.

1. Verify Copilot license assignment in the admin center
   Sign in to the Microsoft 365 admin center with a Global Admin or Billing Admin account. Go to Billing > Licenses. Select the Copilot product name, either Copilot Pro or Copilot for Microsoft 365. On the Assigned licenses tab, confirm the affected user appears in the list. If the user is missing, select Assign licenses, choose the user, and assign the Copilot license. Wait 15 minutes for the license to propagate, then restart the Microsoft 365 client application.
2. Check service health for an active outage
   In the same admin center, go to Health > Service health. Filter the list by the product name “Copilot.” If you see an advisory with a status of “Service degradation” or “Service interruption,” click the advisory to read the details. Microsoft will post an estimated resolution time. No client-side action is needed in this case. Wait for the advisory to be resolved.
3. Add Copilot URLs to the network allowlist
   Work with your network administrator to ensure the following URLs are allowed through any proxy or firewall:
   copilot.microsoft.com
api.copilot.microsoft.com
login.microsoftonline.com
graph.microsoft.com
   These are the primary endpoints Copilot uses for authentication, data retrieval, and response generation. If your organization uses a web proxy with SSL inspection, ensure the certificates for these domains are trusted by the client machine. After updating the allowlist, clear the DNS cache on the user’s device by running ipconfig /flushdns in an elevated Command Prompt.
4. Disable VPN or switch to a direct connection
   If you are connected through a corporate VPN, disconnect and try accessing Copilot using a direct internet connection. Some VPN tunnels route traffic through restricted gateways that block the Copilot endpoints. If Copilot works without the VPN, contact your IT team to update the VPN split-tunneling rules to exclude the Copilot URLs listed in step 3.
5. Repair the Microsoft 365 installation
   Open the Control Panel > Programs and Features. Locate Microsoft 365 in the list, right-click it, and select Change. Choose the Quick Repair option. This process re-registers the Copilot add-in components without reinstalling the entire suite. After the repair completes, restart your computer and open the Microsoft 365 application again.
6. Reset the Copilot pane cache
   Close all Microsoft 365 applications. Press Windows + R, type %localappdata%\Microsoft\Office\16.0\OfficeCache, and press Enter. Delete all files and folders inside the OfficeCache folder. This clears the local Copilot pane cache, which sometimes stores stale connection state. Restart the application and test Copilot.

If Copilot Still Has Issues After the Main Fix

Copilot Shows the Error Only in One Application

If the error appears in Word but not in Excel, the issue is likely a corrupt add-in state in that specific application. Run the repair tool from step 5, but this time select the Online Repair option. This performs a full reinstall of the Microsoft 365 suite and replaces all application-specific files. Back up any custom templates or macros before proceeding.

Error Returns After a Few Minutes of Use

This pattern indicates a token expiration or a session timeout caused by a misconfigured Conditional Access policy in Azure AD. Sign in to the Microsoft Entra admin center. Go to Protection > Conditional Access > Policies. Look for any policy that targets the Copilot cloud app. If a policy requires device compliance or multi-factor authentication every 60 minutes, the Copilot token expires and the service becomes unavailable. Adjust the session control settings to a longer duration, such as 8 hours, or create an exclusion for the Copilot app.

Copilot Returns the Error on a Shared or Guest User Account

Copilot does not support guest accounts or B2B collaboration users in most Microsoft 365 plans. If the user is a guest, the Copilot service will always return the unavailable error. The only workaround is to convert the guest user to a full member account with a Copilot license assigned. Contact your Microsoft account representative to confirm guest support for your specific plan.

Copilot License Plans: What You Need to Know

Item	Copilot Pro	Copilot for Microsoft 365
Target users	Individuals and small businesses	Enterprise organizations with Microsoft 365 E3/E5
License cost	$20 per user per month	$30 per user per month
Application support	Word, Excel, PowerPoint, Outlook, OneNote	Same plus Teams, Loop, and Microsoft Graph grounding
Data security	Consumer-grade data handling	Enterprise-grade with Microsoft 365 compliance features
Admin control	None	Full admin policies, usage reports, and Conditional Access

Choosing the wrong license type can lead to the unavailable error. If your organization uses Copilot for Microsoft 365 but a user is accidentally assigned a Copilot Pro license, the service will reject the connection. Verify the license SKU in the admin center under Billing > Licenses to ensure consistency.

The “Microsoft 365 Copilot Service Is Temporarily Unavailable” error is almost always solvable by checking the license assignment, network allowlist, and service health dashboard. Start with the admin center license check because it is the fastest to verify. If the error persists after all steps, run the Online Repair from the Microsoft 365 installation menu. For enterprise environments, review your Conditional Access policies to prevent token expiration issues that cause the error to reappear.