How To: Migrate “Forms” Folder in Sharepoint.
There may be a requirement to migrate a folder having a name as “Forms” but, there is a hidden "Forms" folder already present in each SharePoint document library. The Forms folder is used by SharePoint to store document templates and it is a system-reserved name.
To overcome this, you can either rename that particular folder in the source system before migration or you can follow these steps to rename this folder during migration:
1) Click Folder to Folder Content Type Mapping settings in the migration task settings window:
2) Click on the "Title" field setting to use the below script:
3) Select the script mapping type, provide the name of the script, add the script provided below and then save it.
If($MigrationItem.SI.ItemName -eq "Forms")