How to fix Outlook Calendar 'This meeting cannot be sent' error when adding a meeting room in Microsoft 365

Summary

This guide helps you troubleshoot and resolve: How to fix Outlook Calendar 'This meeting cannot be sent' error when adding a meeting room in Microsoft 365. Follow the steps below to fix the issue.

Common Causes

When you add a meeting room resource to a calendar invitation in Microsoft Outlook and receive the error “This meeting cannot be sent,” it usually means Outlook cannot validate the room mailbox or connect to the Exchange server to check availability. This is a common issue for small businesses using Microsoft 365 and can often be resolved by refreshing your Outlook profile, checking room settings, or updating your client.

Quick Fix Steps

1. Close Outlook completely and reopen it.
2. Create a new meeting invitation and try adding the room again.
3. Check your internet connection and ensure you are signed into Microsoft 365.
4. If the error persists, follow the detailed instructions below.

Detailed Instructions

1. Check the Room Resource in Outlook Web Access

1. Open a web browser and go to https://outlook.office.com.
2. Sign in with your Microsoft 365 email address and password.
3. Select the Calendar icon from the left navigation.
4. Click New event.
5. Click Add room or Add location and select the meeting room.
6. Send a test invitation to yourself.

If the invitation sends successfully in Outlook on the web, the issue is likely with your desktop Outlook application.

2. Update Outlook and Clear Cached Credentials

1. Open Outlook on your desktop.
2. Go to File > Office Account (or File > Account).
3. Under Product Information, select Update Options > Update Now.
4. Restart Outlook once updates are installed.
5. If you use Windows, open Credential Manager from the Start menu.
6. Look for entries related to microsoft365.com, outlook.office365.com, or your email domain.
7. Remove any outdated or incorrect credentials, then restart Outlook.

3. Verify Room Mailbox Permissions

If you are organising meetings on behalf of another user or managing a shared calendar, ensure your account has permission to book the room:

1. Ask your Microsoft 365 administrator to check the room mailbox in the Exchange admin centre.
2. Confirm the room resource is enabled and accepts meeting requests.
3. Verify your user account has Read and Write permissions to the room calendar if required.

4. Recreate the Outlook Profile

If the error continues, your Outlook profile may be corrupted:

1. Close Outlook.
2. Open Control Panel and search for Mail.
3. Click Show Profiles.
4. Select your profile and click Remove, then confirm.
5. Click Add to create a new profile.
6. Enter your email address and follow the prompts to reconfigure your account.
7. Open Outlook using the new profile and test adding a meeting room.

Troubleshooting

Error occurs only with one specific room

• The room mailbox may be deleted, disabled, or misconfigured.
• Contact your IT administrator to verify the room resource exists in Microsoft 365.

Error occurs on all devices and Outlook on the web

• This indicates an issue with the room resource or your mailbox permissions rather than your local computer.
• Request assistance from your Microsoft 365 administrator.

Outlook is running in Cached Exchange Mode

• Go to File > Account Settings > Account Settings.
• Select your email account and click Change.
• Temporarily turn off Use Cached Exchange Mode, then restart Outlook.
• Test sending a meeting with a room resource.

Meeting room resources are managed by your organisation’s Microsoft 365 administrator. If you do not see a room in the list, it may not have been set up as a bookable resource.

Removing an Outlook profile will delete locally stored data such as draft emails and autocomplete suggestions that have not synchronised to the server. Back up any important local items before removing a profile.

If you continue to receive the “This meeting cannot be sent” error after trying these steps, Open a Ticket with 220 Internet Services support.

Still Having Issues?