Error: A site already exist at url <URL> (4315822)

The error message below is displayed when copying a site or site collection, then pasting it as a site collection to SharePoint Online:

When performing a full copy, Content Matrix overwrites data on the target environment if it matches the content to be migrated. However, one of the following scenarios may cause the issue to happen in SharePoint Online:

• Site collection already exists.
• Site collection is still in the Recycle Bin.
• Site collection does not exist anymore in the site collections list or Recycle Bin, but it is still being detected by SharePoint Online.

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1. Check if site collection still exists in the site collections list of SharePoint Online. If it does, right-click on the target site collection and perform a Paste All Site Content action.
   
   
    
2. Check if site collection still exists in the Recycle Bin. If it does, click here for instructions on how to run Remove-SPODeletedSite to delete the site collection from the Recycle Bin.
3. Recreate the site collection in SharePoint Online, and then perform a Paste All Site Content action. If it cannot be recreated, contact Microsoft for assistance in permanently deleting the site collection.

NOTE: After performing a Full Copy when initially migrating a site collection, it is best to perform an Incremental Copy or Paste All Site Content on succeeding migrations.