This article covers the most common errors that may occur with the MS Exchange Calendar integration and how site administrators can resolve them.
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New to the MS Exchange Calendar integration? Learn more in our MS Exchange Calendar integration overview and setup article.
1. User token expiring due to inactivity
Error message:
invalid_grant → AADSTS700082: The refresh token has expired due to inactivity. The token was issued on [date] and was inactive for 90.00:00:00.
What happened: If the MS Exchange integration hasn't been used for an extended period, the user token that keeps the connection active expires.
How to solve it:
- Go to Settings > Site settings > Integrations > MS Exchange and click the Disconnect button.
- Reconnect the integration by clicking Connect to MS Exchange and logging in again. Once reconnected, events will start syncing normally again.
2. Lack of permissions (403 Forbidden)
Error message:
Client error: 'GET https://graph.microsoft.com/v1.0/me' resulted in a '403 Forbidden' response: {"error":{"code":"Authorization_RequestDenied","message":"Insufficient privileges to complete the operation."...}
What happened: This error occurs when a user tries to connect MS Exchange but the connected account doesn't have the necessary permissions granted in Azure.
How to solve it: Add the necessary permissions via Azure portal by MS Exchange administrator. Learn more about what permissions are required and how to add the permissions.
3. Error due to password change (invalid_grant)
Error message:
Connecting failed: invalid_grant → AADSTS50173: The provided grant has expired due to it being revoked, a fresh auth token is needed. The user might have changed or reset their password.
What happened: If a user changes or resets their Microsoft account password, their existing integration token becomes invalid.
How to solve it:
- Go to Settings > Site settings > Integrations > MS Exchange and click the Disconnect button.
- Reconnect the integration and log in with the updated credentials.
- If reconnecting doesn't resolve the issue, ask your IT department to confirm the account still has the necessary permissions.
4. Application is over its MailboxConcurrency limit
Error message:
Application is over its MailboxConcurrency limit.
What happened:
This error appears when too many requests are sent to Exchange at once — typically when a large number of recurring events (with multiple participants) are created in Scoro at the same time. Since Exchange sends an email notification for each event to all participants, one mailbox can hit Microsoft's rate limit for outgoing notifications, triggering this error in the Logs tab.
How to solve it: If the issue is caused by bulk recurring event creation, consider one of these approaches:
- Split event creation across users: Have different users create their own recurring events, spreading the sync load across multiple mailboxes. Note: if a user later edits a recurring event they created, the change only applies to their own calendar — other participants must be notified separately.
- Stagger creation over time: If one user needs to create recurring events for the whole team, split the work into batches per month rather than creating a full year's worth at once.
- Resync manually: Compare events on both sides, identify mismatches, and re-save them individually to trigger the sync again — or simply wait 24 hours for Exchange's limit to reset. The next scheduled sync will pick up any notifications that weren't sent.