This article explains how to resolve the ErrorFolderExists error, which is caused by a folder name conflict with a protected, system-level folder in the destination Microsoft 365 or Exchange environment.
1. Symptom
When running a migration to Microsoft 365 or an on-premises Exchange Server, the process fails when attempting to create a folder. The migration logs show the following error:
Service Exception processing request. Code: ErrorFolderExists, Message: A folder with the specified name already exists.
2. Cause
This error occurs when a folder in the source mailbox has the same name as a default, special-purpose folder that already exists in the destination Exchange mailbox. These default folders are protected by Microsoft and can only contain specific item types (e.g., the Calendar folder can only contain calendar items).
The most common example is a source email folder that a user has named "Notes". Every Exchange mailbox includes a default "Notes" folder, but it is a special folder type designed only to hold Outlook Notes items, not emails.
When CloudM Migrate attempts to create a new email folder named "Notes", Exchange blocks the action because a protected folder with that name already exists. The tool cannot merge the contents because emails cannot be placed into the special Notes folder.
Other protected default folder names include:
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Calendar
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Contacts
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Tasks
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Journal
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Drafts
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Sent Items
3. Resolution
Because the destination folder names are protected, the only solution is to rename the conflicting folder in the source mailbox before migrating.
Step 1: Identify the Conflicting Folder
Review the CloudM Migrate logs to identify the name of the folder that is causing the ErrorFolderExists error.
Step 2: Rename the Source Folder
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Log in to the user's source mailbox.
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Locate the folder identified in the logs (e.g., "Notes").
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Rename the folder to something that does not conflict with a default system folder. Good examples include "Archived Notes" or "Project Notes".
Step 3: Re-run the Migration
Once the folder has been renamed at the source, you can re-run the migration for the user in CloudM Migrate. The tool will now be able to create the newly-named folder (e.g., "Archived Notes") and migrate its contents without conflict.